Modification de Europe at the centre of the world: from the end of the 19th century to 1918

{{Translations
| fr = L’Europe au centre du monde : de la fin du XIXème siècle à 1918
| es = Europa en el centro del mundo: de finales del siglo XIX a 1918
| it = L'Europa al centro del mondo: dalla fine del XIX secolo al 1918
| de = Europa im Zentrum der Welt: Vom Ende des 19. Jahrhunderts bis 1918
}}

{{Infobox Lecture
 | image = 
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 | cours = [[Introduction à l'histoire des relations internationales]]
 | faculté = [[Lettres]]
 | département = [[Département d’histoire générale]]
 | professeurs = [[Ludovic Tournès]]<ref>[https://www.unige.ch/lettres/istge/unites/hco/enseignants-chercheurs/tournes/ Page personnelle de Ludovic Tournès sur le site de l'Université de Genève]</ref><ref>[https://www.cairn.info/publications-de-Tourn%C3%A8s-Ludovic--5840.htm Publications de Ludovic Tournès | Cairn.info]</ref><ref>[http://sirice.eu/membre/ludovic-tournes CV de Ludovic Tournès sur le site de l'Université de la Sorbonne]</ref>
 | enregistrement = 
 | lectures = 
*[[Perspectives sur les études, enjeux et problématiques de l'histoire internationale]]
*[[L’Europe au centre du monde : de la fin du XIXème siècle à 1918]]
*[[L’ère des superpuissances : 1918 – 1989]]
*[[Un monde multipolaire : 1989 – 2011]]
*[[Le système international en contexte historique : Perspectives et interprétations]]
*[[Les débuts du système international contemporain : 1870 – 1939]]
*[[La Deuxième guerre mondiale et la refonte de l’ordre mondial : 1939 – 1947]]
*[[Le système international à l’épreuve de la bipolarisation : 1947 – 1989]]
*[[Le système post-guerre froide : 1989 – 2012]]
}}

Spanning the period from the end of the 19th century to the end of the First World War in 1918, this historic era witnessed the rise of Europe as a global pivot. It was a period marked by major transformations - economic, political, social and cultural - that had a profound impact on global history. At the end of the 19th century, Europe was controlled by major colonial powers, including mainly the United Kingdom, France, Germany and Italy. These nations extended their reach across the globe, and their rivalries for control of colonial territories and world markets led to an arms race and rising tensions on the European continent. 

It is fair to say that Europe was a key player on the international stage right up to the end of the First World War in 1918. This pre-eminence was due to a combination of factors, including Europe's economic and colonial dominance on a global scale, the antagonism between the great European powers, and their direct influence on world political events.

However, the First World War led to a significant decline in European influence in international affairs. The conflict devastated the continent's economies and infrastructure, leading to a weakening of its economic and political power. The war also saw the emergence of new powers such as the United States and the Soviet Union. In addition, the repercussions of the First World War catalysed the rise of nationalist movements and authoritarian regimes in Europe, jeopardising the region's political stability. The advent of Nazism in Germany in the 1930s led to the Second World War, marking a new phase of decline for Europe. So, although Europe reigned supreme in international relations until the end of the First World War, this conflict caused a redistribution of the global balance and signalled the beginning of a decline in Europe's influence on the international stage.

= The European System and Order =
The European system established at the Congress of Vienna in 1815 was largely dominated by five major powers - France, the United Kingdom, Russia, Austria and Prussia. This system, sometimes referred to as the Concert of Europe, was designed to maintain the balance of power in Europe after the upheavals of the Napoleonic Wars. The Congress created a new map of Europe, redefining the borders of nations and seeking to balance the interests of the great powers to prevent further large-scale conflict. In theory, these powers undertook to respect the principles of national sovereignty and territorial integrity, and to resolve their differences through negotiation rather than war. However, during the 19th century, this system came under severe pressure. Historic nation-states such as France and Great Britain coexisted with newly emerging nation-states such as Italy (unified in 1861) and Germany (unified in 1871). At the same time, multinational empires such as the Austro-Hungarian Empire, the Russian Empire and the Ottoman Empire continued to exist, generating a series of complex tensions.

The balance of power established by the Congress of Vienna proved unstable. The great powers, seeking to extend their influence and territory, provoked growing diplomatic and military tensions. Prussia, for example, under the leadership of Otto von Bismarck, succeeded in unifying Germany and establishing it as a great power, thereby altering the balance of power in Europe. At the same time, the break-up of the Ottoman Empire created a power vacuum in the Balkans, leading to conflict and rivalry for control of this strategic region. Rivalries between the great powers eventually led to a series of military alliances to prevent aggression from others. However, far from preventing conflict, these alliances created a complex web of obligations that actually exacerbated tensions. The Triple Entente (made up of France, Russia and the United Kingdom) and the Triple Alliance (made up of Germany, Austria-Hungary and Italy) were ultimately the protagonists of the First World War in 1914, putting an end to the balance of power that had been established a century earlier.

From the end of the 19th century to the end of the First World War in 1918, Europe stood out as the beating heart of the world. This period was characterised by far-reaching social, economic and political transformations that profoundly reshaped the European landscape and the international system. The European system of this period was characterised by exacerbated rivalry between the European powers, struggling for control of colonies, markets and natural resources. Imperialism and competition for overseas territories fuelled tensions, leading to an arms race and strategic alliances. The great powers of the time, including the United Kingdom, France, Germany, Austria-Hungary and Russia, established alliances and agreements to safeguard their interests and strengthen their position on the international stage. Systems of alliances, such as the Triple Entente (United Kingdom, France, Russia) and the Triple Alliance (Germany, Austria-Hungary, Italy), shaped European geopolitics, creating a complex web of relationships that eventually led to the First World War. In this way, this period in European history illustrates how Europe became the pivot of the world stage, as a result of internal political dynamics, imperialist ambitions and the system of alliances that was put in place among the great powers.

The European order during this period was profoundly influenced by several major events, such as the Franco-German War of 1870-1871 and the Russo-Japanese War of 1904-1905. The inauguration of the German Empire in 1871, following the defeat of France and the annexation of Alsace-Lorraine by Germany, considerably heightened tensions between the European powers. These tensions led to the creation of protective alliances and unbridled competition to build up military capabilities. At the same time, the international system underwent major upheavals. The rise of the United States and Japan as new economic and military powers injected a new dynamic into international relations, challenging the traditional supremacy of the European powers and redrawing the balance of power on a global scale. The First World War, which began in 1914, marked the culmination of these tensions and rivalries. This major conflict not only put an end to the European order of the time, but also indelibly transformed the international system. It led to the weakening of the European powers, the rise of the United States and the Soviet Union, and laid the foundations for a new world order in the 20th century.

In the 19th century, Great Britain emerged as the leader of the industrial revolution, becoming the world's leading industrial power. Textile, steel and mining industries flourished, underpinning the national economy and providing employment for millions of workers. This industrial upheaval not only had an economic impact, it also profoundly changed the face of Britain, both domestically and internationally. On a national scale, the Industrial Revolution brought about a profound social transformation. The urban landscape was transformed by massive urbanisation, accompanied by explosive population growth and the emergence of new social classes. While this industrial revolution improved living conditions for some, it also accentuated social and economic inequalities, creating a growing gap between industrial workers and the ruling class. Internationally, the Industrial Revolution greatly enhanced Britain's status as a global superpower. Thanks to the economic power derived from its industrial dominance, Britain was able to extend its control over its vast colonial empire, consolidating its influence around the world. At the same time, Britain's economic power enabled it to develop a powerful navy, essential for the protection of its economic interests and colonies around the world. Britain used this naval power to secure its trade routes and extend its diplomatic and political influence beyond its borders.

The Industrial Revolution brought about a significant transformation in global power dynamics. Whereas powerful Asian empires such as India and China had previously dominated the global economy, the industrial rise of Europe altered this balance. As a result, the centre of global economic and political influence has shifted from Asia to Europe. However, European dominance was short-lived. Despite its pre-eminent position at the beginning of the 20th century, European hegemony began to crumble with the conclusion of the First World War in 1918. Several factors contributed to this decline. Firstly, the enormous toll of the war in terms of loss of life, material destruction and financial expenditure exhausted the great European powers. This weakened the economies of Europe, creating space for the rise of new powers, notably the United States. In addition, the war stimulated the emergence of nationalist and revolutionary movements both in Europe and in its colonies, challenging the European imperial order. For example, the Ottoman Empire was dismantled and India began to demand independence from Great Britain. Finally, the end of the war also led to the creation of new international institutions, such as the League of Nations, which sought to establish a new world order based on international cooperation rather than imperial domination. This new order ushered in a paradigm shift in global power, shifting influence from Europe to the United States and the Soviet Union, which became the new superpowers after the Second World War.

The dawn of the twentieth century was a crucial turning point in global history, marking the end of the European supremacy that had prevailed until then. Several factors contributed to this change of direction. The First World War inflicted considerable damage on the great European powers. The conflict drained their resources, caused catastrophic loss of life and spawned social and political movements on an unprecedented scale, shaking the status quo and diminishing Europe's weight on the world stage. This period also saw the emergence of new global forces that challenged European dominance. The United States, Russia and Japan strengthened their positions as economic and military powers, creating new centres of power and influence. Within Europe itself, a number of challenges have exacerbated the decline. The rise of nationalism and growing tensions between the great European powers have undermined the unity of the continent. In addition, the political and social upheavals that followed the First World War accelerated the process of decline. The rise of communism, independence movements in the colonies and the emergence of new political ideologies, such as fascism and Nazism, profoundly reshaped the global political landscape. In short, the end of European hegemony at the beginning of the twentieth century was the result of a complex interweaving of factors. They include the First World War, the rise of new economic and military powers, Europe's internal challenges and post-war political and social upheaval. These events ushered in a new era, during which the centre of global power gradually migrated from Europe to other parts of the world.

== The Concept of the State System ==
The Treaty of Westphalia, signed in 1648, marked a decisive turning point in the way international relations are structured. It put an end to the Thirty Years' War, a series of religious and political conflicts that devastated central Europe. However, its impact went far beyond the mere cessation of hostilities. One of the most important achievements of the treaty was the introduction of the concept of the sovereign nation state, which became the fundamental building block of the global political order. This concept stipulated that each state had supreme authority within its borders and that no other state should interfere in its internal affairs. This principle was also reinforced by the concept of the equality of states, according to which all states, large or small, have the same rights and are equal under international law. Before Westphalia, Europe was dominated by the idea of the universal empire, which was an attempt to recreate the political order of the Roman Empire. According to this vision, there was a hierarchical order with a single leader, such as the Holy Roman Emperor or the Pope, who exercised supreme authority over the kings and princes of the whole of Europe. The Treaty of Westphalia overturned this vision by establishing the nation state as the principal political unit. This gave greater autonomy to individual states and laid the foundations for the modern interstate system. This system, which persists to this day, is based on the principle of state sovereignty, non-interference in the internal affairs of other states and the legal equality of all states. 

The establishment of the principle of state sovereignty, enshrined in the Treaty of Westphalia, radically transformed the landscape of international relations. From then on, each state was master of its own internal affairs, creating a new dynamic between nations. By recognising that each state had the right to govern itself without outside interference, the Treaty of Westphalia established mutual respect for national independence and autonomy. This principle of non-interference gave rise to a new international order, characterised by a system of checks and balances. Under this system, states sought to maintain international balance by ensuring that no state or alliance of states became too powerful. This balance was maintained through constantly evolving alliances and limited wars, as nations sought to prevent the domination of any single actor.

The Treaty of Westphalia marked the end of an era for the Holy Roman Empire, a complex and disparate set of political entities that had dominated Central Europe for several centuries. The Thirty Years' War, with its chaos and destruction, had undermined the structure and authority of the Holy Roman Empire, creating a political vacuum. By signing the Treaty of Westphalia, European leaders recognised the independence of the many German states that had previously made up the Holy Roman Empire. These newly autonomous political entities were able to take control of their own destiny, marking the birth of the modern system of nation states in Europe. This new system was strongly rooted in the principle of state sovereignty, stipulating that each state had the right to conduct its internal and external policies without external interference. In addition, it adopted the principle of the balance of power, according to which no state or group of states should be powerful enough to dominate others. This paradigm shift not only redefined relations between the German states, but also had a profound impact on the political structure of Europe and the world as a whole. The principles of the Treaty of Westphalia helped shape the international system we know today, based on mutual recognition of sovereign states and respect for their political autonomy.

In the wake of the Treaty of Westphalia, European states structured their interactions around a series of bilateral and multilateral relationships. By forging alliances based on common interests and concluding diplomatic agreements, they sought to maintain a balance of power in order to avoid major confrontations. This created a complex web of obligations and responsibilities that shaped European politics for several centuries. However, this system of nation states began to show signs of strain at the dawn of the twentieth century. The arms race, imperial rivalry and nationalist tensions fuelled conflict and made it increasingly difficult to maintain a balance of power. The First World War marked a dramatic break in this dynamic. Not only did the conflict result in the loss of millions of lives and the destruction of large parts of Europe, it also called into question the very principles on which the nation-state system was based. The consequences of the war prompted world leaders to seek new ways of managing international relations, leading to the creation of the League of Nations and later the United Nations, marking the beginning of a new international order.

The Treaty of Westphalia enshrined a number of key principles that have shaped international relations to this day.
* The first, the balance of power, aimed to prevent the domination of one nation over another by maintaining a balance of power between states. It encouraged the creation of alliances and coalitions to counter any attempt at hegemony by a single entity and to prevent major conflicts.
* The second principle, that of non-interference, developed naturally from the concept of state sovereignty. Under this concept, each state is free to manage its internal affairs without outside interference, except in the event of a threat to collective security.
* Finally, the principle of "Cujus regio, ejus religio" established that the religion of the sovereign determined that of the State, but also granted individuals the right to practise their religion freely. This clause was intended to put an end to the wars of religion that had severely fragmented Europe.

These principles not only reinforced political borders, but also restructured the hierarchy of powers in Europe. Nation states emerged as autonomous and sovereign political entities, with their own political, economic and military systems. At the same time, religion, while remaining an important element in the lives of many Europeans, gradually lost its political influence to political ideologies such as nationalism, liberalism and socialism.

These principles of the Treaty of Westphalia were the mainstay of European political organisation for almost two centuries. However, they have been severely tested throughout history. The Napoleonic Wars and then the First World War profoundly upset the balance of power in Europe. In addition, the emergence of nationalist movements and territorial disputes have often challenged the principle of non-interference, putting the sovereignty of states to a severe test. The Treaty of Westphalia marked a decisive turning point in the role of the Church in political affairs. Whereas in the Middle Ages, the Church enjoyed major political influence, the Treaty of Westphalia established the pre-eminence of the nation state, reducing the Church to a spiritual authority. This meant the separation of church and state, a fundamental principle that continues to shape European and global politics today.

The post-Westphalian international system, characterised by the independence and sovereignty of states, faced many challenges in the 19th century. Imperial expansion and rivalries between the great powers led to considerable tensions. The Napoleonic Wars certainly upset the balance of power in Europe, but they also paved the way for a reorganisation of the continent at the Congress of Vienna in 1815. The major European powers then established a new balance of power aimed at preserving stability and peace. This system, sometimes referred to as the "European Concert", ensured a degree of stability for much of the 19th century. However, the end of the 19th century and the beginning of the 20th saw the emergence of new tensions. The arms race, imperial ambitions, colonial tensions and growing nationalism led to a deterioration in international relations. These factors gradually undermined the balance of power and eventually led to the outbreak of the First World War in 1914. This conflict marked the end of the world order established at the Congress of Vienna and triggered a profound transformation in international relations.

Competition between states to increase their influence and power has been a central feature of international relations since the establishment of the nation-state system. However, this competition took on an unprecedented scale towards the end of the 19th century with the emergence of dynamic new powers, notably Germany and the United States. These nations challenged the pre-established balance, which was dominated mainly by the great European powers. Moreover, this race for power was not limited to Europe. It became global with colonisation and imperial expansion, where European nations, but also the United States and Japan, competed to establish their dominance over other regions of the world. This rivalry for global ascendancy came to a head with the outbreak of the First World War. The great European powers found themselves engaged in a total war, which not only devastated the belligerent nations but also radically altered the world political map. The war marked the end of the European order and precipitated a profound reorganisation of international relations.

Rivalry between the world powers and escalating tensions finally led to the outbreak of the First World War in 1914, putting an end to the fragile balance of power and stability that Europe had enjoyed until then. The war profoundly transformed the political map of the world, and in the wake of this devastating conflict, a new international order was established. The League of Nations was created with the aim of preserving international peace and security through cooperation and diplomacy. By creating a platform for dialogue between nations, the ambition was to resolve conflicts by peaceful rather than military means. However, despite these noble intentions, this new order was put to the test with the advent of Nazism in Germany and the continuing tensions between the Great Powers. These challenges, which the League of Nations proved unable to address effectively, led to another devastating world war. In the aftermath of the Second World War, the United Nations Organisation (UNO) was created in 1945, in the hope of filling the gaps left by the League of Nations. The UN sought to establish an international system that would promote not only peace and security, but also international cooperation in areas such as human rights and economic development.

Although the traditional European system was shaken by the devastation of the First World War, the concept of the nation state has not lost its relevance and remains at the heart of contemporary international relations. Nevertheless, the role and responsibilities of nation states have changed considerably over time. With the emergence of complex global challenges in the 20th century, such as globalisation, international terrorism and climate change, among others, states have been forced to revise and broaden their scope of intervention. These new challenges, which transcend national borders, have necessitated greater international cooperation in areas hitherto largely left to the discretion of individual states, such as public health, education and environmental protection. These developments have reaffirmed the central role of states in the management of international affairs, but in an increasingly globalised and interconnected context. Consequently, despite the demise of the classic European system, states continue to be key players in international relations. However, they are now doing so within a broader framework, which goes beyond political and military issues to encompass a multitude of areas affecting the well-being of the world's population.

== Nation-States vs. Empire-States ==

Nation states and empire states have different characteristics. 

A nation state is a type of political structure that has a largely homogenous population in terms of culture, history and language, and has defined and recognised borders. The government of this state has legal sovereignty over this territory and is recognised by other nation states. France, Germany and Japan are typical examples of nation states, in the sense that they have a distinct national identity based on shared culture, language and history. These unifying elements contribute to a strong and cohesive national identity.

An empire state is a political structure made up of various nations, ethnic or linguistic groups, often brought together by conquest. Unlike nation states, empire states can extend over vast territories and encompass a wide variety of cultures, histories and languages. Russia is a good example of a modern empire state, as it spans a large part of Eurasia and is home to a diversity of peoples and cultures. Historically, the Russian Empire, and later the Soviet Union, sought to integrate these diverse groups into a single state, sometimes by force. The Ottoman Empire is another example of a historical empire-state. From the 14th century until the end of the First World War, the Ottoman Empire controlled a vast territory that spanned three continents and included diverse peoples and cultures, including Turks, Arabs, Greeks, Armenians and many others. In these states, power was generally centralised in the hands of a ruling elite, which could be perceived as alien or even oppressive by certain groups within the empire. This can lead to tension and conflict, as we saw with the many nationalist movements that emerged in European empires in the 19th and 20th centuries.

Nation states and empire states have different histories in Europe.

The 19th century in Europe was marked by the nationalism movement, which promoted the idea that each nation, defined by a common language, culture, history and values, should have its own independent state. This movement played a key role in the emergence of modern nation states and the redefinition of political boundaries in Europe. In Germany, for example, the unification process was largely led by the Kingdom of Prussia under Chancellor Otto von Bismarck. Through a series of wars and political manoeuvres, Bismarck succeeded in uniting the various German states into a single nation, creating the German nation-state in 1871. Similarly, in Italy, the unification process known as the Risorgimento led to the unification of several small states and kingdoms into a single Italian nation in 1861. This process was guided by various leaders and political movements, the most notable of which was probably Giuseppe Garibaldi and his Army of a Thousand.

Empires have had a significant presence in European and world history, often extending over immense territories and encompassing a multitude of ethnic, linguistic and religious groups. These imperial states, unlike nation states, were not based on a single, shared national identity, but were often the result of conquest and territorial expansion. The German Roman Empire, which existed from the tenth century until its dissolution in 1806, was a complex political structure comprising numerous kingdoms, duchies, principalities, free cities and other political entities. Despite its name, it was not a homogeneous empire, but rather a collection of more or less autonomous territories that were united under the authority of the Germanic Roman Emperor. The Ottoman Empire, for its part, was one of the most powerful empires in history, extending at its height over three continents (Europe, Asia and Africa) and lasting for more than six centuries (from the end of the 13th century until the end of the First World War in 1918). This empire was a mosaic of peoples of different religions, languages and cultures, and its governance was often marked by tensions between the imperial centre (the Sublime Porte) and the provinces. Managing ethnic, religious and linguistic diversity was often a major challenge for these empires. While some adopted policies of assimilation or suppression of local identities, others opted for more decentralised systems of governance, allowing a degree of autonomy to different regions or ethnic groups. However, tensions and conflicts were often inevitable, particularly during periods of crisis or imperial decline.

Both nation states and empire states have had profound and lasting influences on the course of European and world history.

The emergence of nation states has often been linked to national liberation movements and the assertion of a specific national identity. These movements have often been inspired by ideals of freedom, democracy and self-determination. Nation states are often seen as the ideal framework for democracy, as they allow a community of people with a common language, culture and history to govern themselves. However, they have also often been marked by internal conflict and ethnic tensions, particularly in cases where national borders do not correspond to ethnic divisions.

Empire states, on the other hand, have often been associated with imperialism and foreign domination. They have been characterised by centralised and often authoritarian systems of government, and have often been built by force and conquest. However, they also created areas of stability and relative peace, and often encouraged trade and cultural exchange over vast regions. In addition, some empires established relatively efficient systems of administration and left lasting legacies in the fields of art, science and philosophy.

=== Traditional Nation-States ===

==== The United Kingdom ====
The United Kingdom played a central role in European and world politics during the 20th century, thanks to its industrial and naval power, its vast colonial empire and its dominant position in world trade and finance. The Industrial Revolution, which began in the UK at the end of the 18th century, transformed the British economy and enabled the country to become the "factory of the world". British industry, based on coal and iron, produced a wide range of manufactured goods that were exported around the world. The UK was also a world centre for technological and scientific innovation, with advances in fields such as engineering, chemistry and biology. As the world's leading naval power, the UK controlled key sea routes and protected its commercial interests around the world. Its navy played a key role in the defence of the British Empire, which spanned every continent and included territories such as India, Canada, Australia, South Africa and many islands in the Caribbean and the Pacific. However, the United Kingdom also faced challenges during the nineteenth century. The question of Ireland, where a large proportion of the population aspired to independence, was a constant source of tension. In addition, the rise of new industrial powers, notably Germany and the United States, began to challenge the United Kingdom's dominant position at the end of the century. At the same time, social and political movements within the UK, such as the universal suffrage movement and the workers' movement, also challenged the status quo and led to significant changes in British society.

==== Austria ====
Austria was a continental empire that played an important role in Napoleon's defeat. It was ruled by Emperor Francis I, who was also King of Hungary and Bohemia. By the end of the 18th century, Austria was a major power in Europe and its capital, Vienna, was an important cultural centre. At the Congress of Vienna, Metternich, the Austrian Foreign Minister, played a decisive role in the reorganisation of Europe. He was in favour of a balance of power between the great European powers to avoid any one state dominating the others. He also wanted to restore the old monarchical regimes and crush any hint of revolution. As a result, the Congress of Vienna was to redraw the map of Europe by re-establishing the monarchies deposed by Napoleon and creating new nation states such as Belgium and Norway. Despite this, Austria was to experience difficulties during the 19th century, particularly with the nationalist movements that emerged in the various territories of the Empire, which was made up of many different ethnic groups. This internal instability weakened Austria and contributed to its defeat in the First World War.

Austria was a major power in Europe for several centuries, playing a central role in European affairs. The Austrian Foreign Minister, Prince Metternich, was an influential figure at the Congress of Vienna in 1814-1815, which sought to restore the balance of power in Europe after the Napoleonic Wars. Metternich was a staunch defender of the monarchy and opposed any form of revolution or radical change. However, Austria's multinational empire included many different ethnic groups, including Hungarians, Czechs, Poles, Croats, Serbs, Italians and Germans, among others. This created internal tensions, as many groups aspired to greater autonomy or independence. These tensions erupted in the revolutions of 1848, which shook the empire but were eventually suppressed. Nevertheless, these tensions persisted throughout the nineteenth century and contributed to the instability of Austria-Hungary, as the empire became known after the Austro-Hungarian Compromise of 1867. Ultimately, these tensions, combined with external challenges such as rivalry with Prussia and the rise of Serbian nationalism, led to the collapse of Austria-Hungary during the First World War.

==== Prussia ====
Prussia played an important role in the coalition against Napoleon. After an initial defeat by Napoleonic France at the Battle of Jena-Auerstedt in 1806, Prussia was forced to submit to Napoleon and become a satellite state of the French Empire. However, Prussia finally broke its ties with Napoleon and joined the anti-Napoleonic coalition in 1813. Prussia's participation in the war of the Sixth Coalition was decisive in Napoleon's eventual defeat. Prussian forces played a key role in several important battles, including the Battle of Leipzig in 1813, also known as the "Battle of the Nations", which marked a turning point in the war against Napoleon. In 1815, Prussian forces, commanded by Field Marshal Gebhard Leberecht von Blücher, played a crucial role in helping British and Allied troops achieve final victory over Napoleon at the Battle of Waterloo. Prussia's participation in Napoleon's defeat greatly enhanced its position and prestige in Europe. It paved the way for its later role in the unification of Germany under Prussian leadership in the decades following the Napoleonic Wars.

Prussia played a key role in the unification of the German states in the 19th century under the leadership of Chancellor Otto von Bismarck. The creation of the German Empire in 1871 marked a turning point in European history. Germany became a major economic and military power in Europe, competing with the continent's other great powers, in particular the United Kingdom and France. German unification took place against a backdrop of international tensions and rivalries. The Franco-German War of 1870-1871 not only marked the end of the French Second Empire, but also triggered a series of conflicts and tensions in Europe that led to the First World War. France's loss of Alsace-Lorraine was a persistent source of tension between France and Germany, which ultimately contributed to the outbreak of war in 1914. Overall, the formation of Germany as a nation state profoundly transformed the balance of power in Europe and had a major impact on European and world history in the 20th century.

==== France ====
After the fall of Napoleon in 1815, France was forced to focus on internal reorganisation and consolidation, which included a series of revolutions and regime changes. However, it continued to extend its influence on a global scale through its colonial empire, which expanded considerably during the 19th century. In Europe, France has maintained a significant cultural influence, often being regarded as the cradle of the arts, literature and philosophy. Cities such as Paris served as a focal point for artistic and cultural movements, attracting artists, writers and thinkers from all over the world. Despite its internal political challenges, France also underwent significant economic modernisation during the 19th century. With the development of industry and railways, it saw significant economic growth. However, defeat at the hands of Prussia in the Franco-Prussian War of 1870-1871 had a major impact on France's status as a major European power. The loss of Alsace-Lorraine was a major blow to France, and this defeat eventually led to the end of the Second Empire and the establishment of the Third Republic. This event marked a turning point in French history and served as a catalyst for a period of national introspection and reform.

=== Recently Affirmed Nation-States ===

==== Germany ====
German unification was a complex and conflict-ridden process that took place over several decades. It was largely orchestrated by the Kingdom of Prussia and its Chancellor, Otto von Bismarck. Bismarck used both diplomacy and military force to unify the various German states under Prussian hegemony. One of his strategies was to mobilise German nationalism to unite the German states against common enemies. This was clearly illustrated in the wars against Austria in 1866 (known as the Austro-Prussian War or the Seven Weeks War) and against France in 1870 (the Franco-Prussian War). Interestingly, German unification was a major source of tension in Europe. Austria, which had a large German-speaking population, was not included in the new German Empire. This created some ambiguity about Germany's identity as a nation state and was a source of conflict in the decades that followed.

==== Italy ====
Like Germany, Italy was unified in the mid-nineteenth century, after a series of wars and diplomatic manoeuvres. The movement for Italian unification, known as the Risorgimento, was largely inspired by the ideals of nationalism and liberalism. Italian-speaking populations were scattered across various independent states and kingdoms, as well as territories under foreign control, particularly the Austrian Empire. The Italian Wars of Independence, which took place between 1848 and 1866, were mainly directed against Austria and enabled Italy to gain independence and unification. However, the unification of Italy was incomplete. Some regions with Italian-speaking populations, such as Trentino and Istria (the "Irredent Lands"), remained under Austrian control. These territorial claims were a source of tension in international relations, and Italy eventually succeeded in annexing these territories after the First World War. It is also true that the unification process was often led by a political and military elite, with limited popular participation. However, nationalist sentiment was fairly widespread among the Italian-speaking population, which contributed to the success of unification.

=== The Structure and Role of Empire States ===

==== The multinational empires ====
Multinational empires were quite common in Europe at the time, and they often represented a challenge in terms of managing ethnic, linguistic and religious diversity. The Russian Empire, the Ottoman Empire and Austria-Hungary - are good examples of these challenges. The Russian Empire, which spanned much of Eurasia, included many different ethnic and linguistic groups, including Russians, Ukrainians, Belorussians, Tatars, Georgians, Armenians, Jews and many others. The empire was mainly Orthodox, but also had a large Muslim population, particularly in the Caucasus and Central Asia. The Ottoman Empire was even more ethnically and religiously diverse. It included Turkish, Arab, Kurdish, Greek, Armenian, Jewish and other ethnic groups. The Empire was predominantly Muslim, but also included significant Christian and Jewish populations. Austria-Hungary, also known as the Austro-Hungarian Monarchy, consisted of two separate entities - Austria and Hungary - which were linked by a personal union under the rule of the Austrian Emperor and the Hungarian King. Each entity had its own administration, legislation and education system. Austria-Hungary was also ethnically and linguistically diverse, with Germans, Hungarians, Czechs, Slovaks, Poles, Ruthenians (Ukrainians), Romanians, Croats, Serbs and other ethnic groups. In all these empires, internal tensions were a constant feature, as different groups sought to preserve their culture, language and religion, and often also to gain greater autonomy or independence. These tensions ultimately contributed to the dissolution of these empires after the First World War.

The Congress of Vienna in 1815, which redrew the map of Europe after Napoleon's defeat, re-established the monarchical system in many countries and sought to preserve the balance of power in Europe. This order was led by the great powers of the day - Austria, Russia, Prussia and the United Kingdom - and is often referred to as the "Metternich System" after the Austrian chancellor who played a key role at the Congress of Vienna. This system sought to control the nationalist and revolutionary movements that had spread across Europe following the French Revolution and the Napoleonic Wars. The rulers of the time feared that these movements would destabilise their own countries and threaten the established order. However, this policy of repressing nationalist movements and aspirations for independence often had the opposite effect, fuelling resentment and exacerbating tensions. Over the course of the nineteenth century, these tensions erupted several times, leading to revolutions and wars of independence in many parts of Europe. These conflicts ultimately undermined Metternich's system and led to the rise of the modern nation states we know today.

Nationalism was a key factor in destabilising the established order in Europe during the nineteenth and early twentieth centuries. In many multinational empires, different nationalities began to claim their right to self-determination, leading to internal tensions and, in some cases, revolutions and wars of independence. Austria-Hungary, for example, was a multinational empire made up of many different nationalities, including Hungarians, Czechs, Slovaks, Croats, Serbs, Romanians and others. Each of these groups had its own cultural and linguistic identity, and many aspired to have their own independent nation-state. These nationalist aspirations led to internal tensions and conflicts, and ultimately contributed to the collapse of the empire after the First World War. Similarly, in the Ottoman Empire, the various nationalities under Ottoman rule - notably the Greeks, Armenians and Arabs - began to demand their independence, contributing to the destabilisation of the empire. Finally, imperialism and colonial rivalries between the great European powers also contributed to the rising tensions that led to the First World War. Each power sought to extend its influence and secure its interests, often at the expense of the others, leading to a series of alliances and counter-alliances that ultimately triggered the outbreak of the conflict in 1914.

==== The Austro-Hungarian Empire ====
The Austro-Hungarian Empire, under the leadership of the House of Habsburg, was a major player in Europe for several centuries. However, in the late 19th and early 20th centuries, the empire faced a series of internal and external challenges that eventually led to its collapse. Within the empire, ethnic and nationalist tensions intensified. Many ethnic groups, including Czechs, Slovaks, Serbs, Croats, Romanians and Hungarians, began to demand greater autonomy or even total independence. These tensions were exacerbated by the Austro-Hungarian duality of 1867, which granted more autonomy to Hungary but left many other ethnic groups dissatisfied. Outside the empire, Austria-Hungary also faced challenges. The Austro-Prussian War of 1866 marked a decisive turning point, with Prussia's victory asserting its supremacy over the German states and reducing Austria's influence. At the same time, the empire had to contend with the hostility of Russia and Italy, as well as competition from the Ottoman Empire for control of the Balkans. The outbreak of the First World War in 1914 exacerbated these internal and external tensions. Despite tenacious resistance, the Austro-Hungarian Empire was eventually defeated and imploded at the end of the war in 1918, giving rise to several new nation states in Central and Eastern Europe. 

The Austro-Hungarian Empire faced many internal pressures due to the nationalist aspirations of its various ethnic communities. The Compromise of 1867, which created a dual monarchy by granting greater autonomy to Hungary, may have eased some problems, but it exacerbated others by fuelling the frustrations of other national groups who did not benefit from such privileged treatment. These internal tensions were compounded by a series of external problems, including rivalry with Russia, Italy and Prussia (later to become the nucleus of a united Germany). The defeat of Austria-Hungary in the Austro-Prussian War of 1866 marked a turning point, reducing Austria's influence in German affairs and leaving Prussia as the dominant power. The assassination of Archduke Franz Ferdinand in 1914 triggered the First World War, which finally sounded the death knell for the Austro-Hungarian Empire. At the end of the war, the empire was dismantled and replaced by a series of new nation states, including Czechoslovakia and Yugoslavia, reflecting the nationalist aspirations that had contributed to its downfall. These changes radically altered the political landscape of Central Europe and had profound repercussions on twentieth-century European history.

The Austrian Empire was seriously weakened after its defeat by Prussia in the Austro-Prussian War in 1866. This defeat not only strengthened Prussia's position as the dominant power in the German-speaking world, but also exacerbated internal tensions within the Austrian Empire. Emperor Franz Joseph I had to make concessions to Hungarian leaders, who had agitated for greater autonomy, in order to preserve the integrity of the empire. This led to the Compromise of 1867, which transformed the Austrian Empire into a dual empire, known as the Austro-Hungarian Empire. The Hungarian rulers were given a large measure of autonomy, including their own government and administration, although some matters, such as defence and foreign affairs, remained under common control. However, this solution did not satisfy the many other ethnic groups that made up the empire. Demands for autonomy and independence from various nationalities, including the Czechs, Slovaks, Romanians, Serbs and Ukrainians, continued to destabilise the Austro-Hungarian Empire, eventually contributing to its disintegration after the First World War.

The duality of the Austro-Hungarian Empire created internal tensions. While Austria and Hungary were linked by a common monarchy, each had its own parliament and administration. This structure led to a kind of competition between the two parts of the empire, each seeking to preserve and extend its own interests. This situation was complicated by the fact that the empire was also populated by a large number of other nationalities, who were unhappy with their minority status and sought greater autonomy or even independence. Nationalism played a crucial role in the weakening of the Austro-Hungarian Empire. Many ethnic groups within the empire were influenced by the pan-Slav movement, which sought to unite all Slavic peoples under a single political entity. This was particularly evident in the Balkans, where the empire faced a series of crises and wars during the latter part of the 19th century. The First World War finally proved to be the final blow for the Austro-Hungarian Empire. After the empire's defeat in the war, the various nationalities that made it up managed to gain their independence, leading to the creation of several new states in Central and Eastern Europe.

==== The Russian Empire ====
The Russian Empire was an extremely large and diverse multinational state, spanning much of Eastern Europe, Northern Asia and Central Asia. Russians were the largest ethnic group and Russian was the official language of the empire. However, there were also a large number of other ethnic groups living in the Russian Empire, each with their own language, culture and traditions. These included Ukrainians, Byelorussians, Tatars, Jews, Poles, Balts (Lithuanians, Latvians, Estonians), Georgians, Armenians, Azerbaijanis, Kazakhs, Uzbeks, Turkmen and many others. However, the Russian Empire was not a multicultural state in the modern sense of the term. The various nationalities were generally subject to a policy of "Russification", which sought to promote the Russian language and culture at the expense of other cultures. This policy often created tensions between the Russian government and the various nationalities, and was one of the causes of the unrest that eventually led to the collapse of the Russian Empire in the Russian Revolution of 1917.

The early years of the 20th century were marked by a series of uprisings and revolutions that eventually led to the collapse of the Russian Empire. The 1905 revolution was triggered by a series of strikes, demonstrations and military uprisings. It was sparked by a combination of popular discontent with the Tsarist autocracy, dissatisfaction with economic conditions and reaction to Russia's defeat in the Russo-Japanese War. Although this revolution failed to overthrow the Tsar, it did lead to significant reforms, including the creation of a legislative assembly, the Duma. The 1917 revolution was a period of major political and social unrest that eventually led to the fall of the Russian Empire and the birth of the Russian Soviet Federative Socialist Republic. The revolution began in February (or March, according to the Gregorian calendar) with a series of strikes and demonstrations in Petrograd (now St Petersburg), which quickly developed into a national revolution. Tsar Nicholas II abdicated in March, ending more than 300 years of rule by the Romanov dynasty. These revolutions were fuelled by a variety of factors, including popular dissatisfaction with the Tsar's autocratic rule, economic hardship, social and ethnic tensions, and Russia's catastrophic losses in the First World War.

Imperial Russia was an ethnically and culturally diverse entity, made up of many different nationalities. Tensions between these different groups played an important role in the destabilisation and eventual disintegration of the Empire. During the 19th century, many of these nationalities began to develop a stronger nationalist sentiment. This was fuelled by a combination of factors, including the economic, political and cultural oppression of Imperial Russia, as well as the influence of European nationalist and liberal ideas. In particular, Poles, Finns, Balts, Ukrainians, Georgians, Armenians and various groups in Central Asia and the Caucasus all experienced significant nationalist movements. Some of these movements sought greater autonomy or cultural rights within the Russian Empire, while others sought total independence. When the revolution of 1917 broke out, many of these groups seized the opportunity to push their demands. In the chaos that followed, several national republics emerged, some of which succeeded in gaining lasting independence, such as Finland, Lithuania, Latvia and Estonia. Overall, the national liberation movements played a crucial role in the disintegration of the Russian Empire and helped shape the political landscape of Eastern Europe and Eurasia in the 20th century.

==== The Ottoman Empire ====
The Ottoman Empire became a major target of European imperialist ambitions during the 19th century. The empire, which had once been a major player on the European stage, was gradually weakened by a series of internal revolts, economic problems and wars with its European neighbours. The great European powers, seeking to extend their influence, waged a series of wars and diplomatic conflicts known as the "Eastern Question". These conflicts often revolved around the question of how to deal with the decline of the Ottoman Empire and how to divide up its vast territory. Each major power had its own interests in the Ottoman Empire. Russia, for example, was seeking to extend its influence in the Balkans and had a particular interest in gaining access to the Dardanelles and the Bosphorus to guarantee its fleet access to the Mediterranean. Similarly, Britain and France were also interested in protecting their trade routes and economic interests in the region. The involvement of the great powers often exasperated ethnic and religious tensions within the Ottoman Empire, helping to trigger a series of Balkan wars in the early 20th century. These wars further weakened the Ottoman Empire and paved the way for its eventual dismantling after the First World War.

The Ottoman Empire gradually lost control over various territories during the 19th century. For example, Greece gained its independence after the Greek War of Independence (1821-1832). Similarly, Serbia, Romania, Montenegro and Bulgaria gained increasing autonomy throughout the 19th century, culminating in complete independence following the Balkan Wars (1912-1913). In the 20th century, during the First World War, the Ottoman Empire aligned itself with the central powers (Germany, Austria-Hungary). With the defeat of the central powers in 1918, the Ottoman Empire also collapsed. The Treaties of Sèvres (1920) and Lausanne (1923) officially put an end to the Ottoman Empire, reducing Turkey to its current borders and dividing the rest of the Ottoman Empire between the Allied Powers.

The policy of the United Kingdom and certain other European powers towards the Ottoman Empire was guided by a mixture of rivalry and pragmatism. On the one hand, they wanted to control certain parts of the Ottoman Empire for their own interests. On the other, they were also concerned about the instability that might result from the collapse of the Empire. It was precisely this mix of interests that guided British policy towards the Ottoman Empire. The UK saw the Ottoman Empire as a useful "buffer state" against Russian expansion southwards, which could threaten India, the "pearl in the crown" of the British Empire. For this reason, for much of the nineteenth century, the UK sought to maintain the territorial integrity of the Ottoman Empire. This is known as the "policy of balance", which aimed to preserve a balance of power in Europe by preventing any country (including Russia) from becoming too strong. However, this policy changed over time, particularly with the opening of the Suez Canal, which made Egypt (an Ottoman territory) of vital importance to the UK. This led to the British occupation of Egypt in 1882. In addition, at the beginning of the 20th century, the threat posed by Germany began to replace the Russian threat in British foreign policy. This led to a realignment of alliances, and in the First World War the UK found itself at war with the Ottoman Empire, which had allied itself with Germany. After the war, the UK played a key role in the dismemberment of the Ottoman Empire, taking control of many of its former territories in the Middle East under League of Nations 'mandates'.

== The European Balance of Power ==
[[Image:Congress of Vienna.PNG|right|thumb|200px|The Congress of Vienna by Jean Godefroy.]]

=== The Congress of Vienna (1815) ===
The concept of a balance of power in Europe was central to the political and strategic thinking of European states in the 19th century. This balance was intended to prevent any single country dominating the continent and disrupting the stability of the region. This reflected a reaction to the Napoleonic Wars, when Napoleon's expansionist ambitions had destabilised the continent. The Congress of Vienna, which took place in 1814-1815 after the fall of Napoleon, was a key moment in establishing this concept of a balance of power. The European powers, in particular Austria, Russia, Prussia and the United Kingdom, redrew the map of Europe in the hope of creating a balance that would discourage future wars.

The main aim of the Congress of Vienna, which took place from November 1814 to June 1815, was to restore political and military balance in Europe after the upheaval caused by the Napoleonic Wars. This congress was a major attempt at multilateral diplomacy and the participants sought to restore the old order after the collapse of the Napoleonic Empire. One of the main decisions taken at the congress was to contain France to prevent it from causing further unrest in Europe. France's borders were reduced to what they had been in 1790, before the wars of the French Revolution. In addition, France's neighbours were strengthened. For example, the Netherlands was enlarged by incorporating Belgium to create a more powerful Kingdom of the Netherlands. Great Britain played a key role in the Congress. It was one of the great powers that helped defeat Napoleon, and it played an important role in the negotiations. With its extensive maritime and commercial empire, Britain was a key player in maintaining the balance of power in Europe.

During the 19th century, various diplomatic conferences and congresses were organised to manage international tensions and conflicts. These meetings were often dominated by the major European powers, who sought to maintain a balance of power and avoid large-scale war.

=== The Paris Congress (1856) ===
The Congress of Paris is precisely one significant event in nineteenth-century Europe that reflected the tension and concerns about the balance of power. The Congress of Paris (1856) is a notable example of how European powers sought to regulate conflict and avoid the domination of a single power. The Crimean War was an opportunity for the European powers to curb the expansion of the Russian Empire, seen at the time as a threat to the balance of power in Europe. The Congress of Paris attempted to introduce modern principles of international law. For example, the prohibition of privateering (i.e. allowing private ships to conduct hostilities in time of war) was established in the treaty. Despite the settlement of the Crimean War, persistent tensions in the Balkans and the question of the Orient continued to threaten peace in Europe, eventually leading to further conflicts in the region.

The Crimean War (1853-1856) was a significant moment in the history of the 19th century, not only in terms of its impact on the balance of European power, but also because of its repercussions on the conduct of war and international relations. The war pitted Russia against a coalition of states made up of France, the United Kingdom, the Ottoman Empire and the Kingdom of Sardinia. The main issue was control of the Bosphorus and Dardanelles straits, which were essential for Russia's access to the Mediterranean Sea. This was an issue of great strategic importance, as it affected Russia's ability to project its influence and maintain its presence in the Mediterranean. After several years of fighting, the warring parties concluded peace at the Congress of Paris in 1856. In the resulting treaty, Russia was forced to relinquish its claims to the territories of the Straits as well as Moldavia and Wallachia. The treaty also established the neutrality of the straits, allowing all merchant ships through in peacetime and prohibiting warships from entering in peacetime. These provisions greatly limited Russia's influence in the region and underlined the importance of maintaining the balance of power in Europe. However, as is common in diplomatic agreements, underlying tensions and unresolved ambitions continued to exist and helped to fuel future conflicts in the region.

The Treaty of Paris of 1856 marked the end of the Crimean War, with several important provisions aimed at maintaining peace and stability in Europe. In addition to the conditions mentioned concerning Russia, the treaty also established several other principles and rules:

* The neutralisation of the Black Sea: The treaty stipulated that the Black Sea was neutral, meaning that no warships could be present there in peacetime. This provision limited Russia's influence in the region and was intended to prevent future conflicts.
* The guarantee of the territorial integrity of the Ottoman Empire: The European signatory powers agreed to respect the territorial integrity of the Ottoman Empire, with the aim of preventing the break-up of the empire and any conflicts that might ensue.
* Protection of Christians in the Ottoman Empire: The treaty also provided guarantees for the protection of Christians in the Ottoman Empire, which was a matter of concern for several European powers.
* Recognition of Romania, Serbia and Montenegro: The treaty also recognised the independence of Romania, Serbia and Montenegro, which had previously been under the control of the Ottoman Empire.

However, although the Treaty of Paris brought a degree of stability to Europe in the short term, the underlying tensions between the European powers and nationalist aspirations in the Ottoman Empire and elsewhere persisted, leading to further conflict in the decades that followed.

=== The Congress of Berlin (1878) ===
The Treaty of San Stefano, signed on 3 March 1878 at the end of the Russo-Turkish War of 1877-1878, provided for major territorial concessions from the Ottoman Empire and created an autonomous Bulgarian state under Russian influence, extending into the Balkans. The European powers, in particular Great Britain and Austria-Hungary, were concerned about the imbalance of power this would create in the region and the increased influence of Russia. Consequently, they convened the Congress of Berlin in June and July 1878 to revise the terms of the Treaty of San Stefano.

The Congress of Berlin led to the signing of the Treaty of Berlin, which considerably reduced the size of the Bulgarian state created by the Treaty of San Stefano and placed part of its territories under the control of the Ottoman Empire or other European powers. The treaty also recognised the complete independence of Romania, Serbia and Montenegro from the Ottoman Empire, assigned Bosnia-Herzegovina to the administration of Austria-Hungary and granted Great Britain control of Cyprus. The Congress of Berlin and the resulting treaty were important events in the history of international relations, as they reconfigured the political map of the Balkans and had a significant impact on the balance of power in Europe. However, they failed to definitively resolve nationalist tensions and power rivalries in the region, which contributed to subsequent conflicts, including the Balkan Wars and the First World War.

The Congress of Berlin significantly altered the political landscape of the Balkans, while seeking to maintain a certain balance of power between the various European nations. The Bulgarian state, which had been considerably enlarged by the Treaty of San Stefano, was divided into three parts by the Treaty of Berlin. Bulgaria itself became an autonomous principality under Ottoman suzerainty, eastern Rumelia obtained autonomous status under the direct control of the Ottoman Empire, and Macedonia returned to the authority of the Ottoman Empire. The Congress of Berlin also extended the territory of Serbia and Montenegro and recognised their independence, as well as that of Romania. Austria-Hungary, for its part, obtained the right to occupy and administer Bosnia-Herzegovina, even though it officially remained a province of the Ottoman Empire. These changes had long-term consequences for the Balkans and for Europe in general, exacerbating nationalist tensions and territorial conflicts, and paving the way for future crises.

=== The Algeciras Congress (1906) ===
The Congress of Algeciras was convened on the initiative of German Chancellor Bernhard von Bülow following the Tangiers crisis of 1905, when Kaiser Wilhelm II declared his support for Moroccan independence, thereby challenging France's growing control over the country. This declaration led to a serious diplomatic crisis between France and Germany. At the Algeciras Congress, the majority of participating countries supported France's position. The result was recognition of France's "freedom of action" in Morocco, while officially maintaining the Sultan's sovereignty. Germany was forced to accept a compromise that included respect for commercial freedom in Morocco, as well as the establishment of an international police force led by French and Spanish officers to maintain order. The event was a diplomatic setback for Germany and contributed to the country's international isolation. It also marked a rapprochement between France and the United Kingdom, who had already drawn closer with the Entente Cordiale of 1904, reinforcing the opposition between the Allies (France, United Kingdom, Russia) and the Central Powers (Germany, Austria-Hungary, Italy) that was to lead to the First World War.

The Congress of Algeciras reflected and intensified the tensions between the great powers, particularly between France and Germany. While the Congress confirmed France's privileged position in Morocco, it also formalised a system of international control, in principle intended to guarantee the economic rights of other nations and preserve Morocco's formal independence. In practice, however, the Congress mainly validated France's growing influence over Morocco, which was perceived as a setback for Germany. This fuelled resentments and tensions that ultimately contributed to the escalation of hostilities that led to the First World War. It is also important to note that the Congress of Algeciras was an early example of US involvement in European affairs, foreshadowing its growing role on the international stage during the twentieth century.

The growing tension between the European powers at the beginning of the 20th century threatened the balance of power established at the Congress of Vienna. A major factor in this instability was the rapid rise of Germany as a major economic and military power under the leadership of Kaiser Wilhelm II and Chancellor Otto von Bismarck. Germany sought to expand its influence, which led to tensions with other great powers, particularly Britain and France. Growing nationalism in Europe also played an important role. Many populations began to claim their right to self-determination, which created tensions in regions such as the Balkans. In addition, the arms race, particularly between Germany and Great Britain, helped to create a climate of mistrust and rivalry. The development of new military technologies and the strengthening of armies have increased the potential for destruction in the event of conflict. All these factors contributed to an escalation of tensions that eventually led to the outbreak of the First World War in 1914, signifying the end of the European balance of power as conceived in 1815.

== The Emergence of the New Global Powers ==
In the second half of the 19th century, the world began to experience a significant redistribution of power on a global scale. Both the United States and Japan began to emerge as influential global players.

The Spanish-American War marked a key stage in the United States' rise to power on the international stage. The US victory not only led to the annexation of Puerto Rico, Guam and the Philippines, but also confirmed America's status as a colonial power. It also formalised American domination of Cuba and gave the United States significant influence over the political and economic affairs of Latin America, notably through the Monroe Doctrine, which established Latin America as a sphere of American influence.

Japan, for its part, became a major world power after its victory over Russia in the Russo-Japanese War of 1904-1905. This war marked the first time that an Asian nation had defeated a European power in a modern military conflict, and it radically changed perceptions of the balance of power in the world. Japan further strengthened its position with the annexation of Korea in 1910.

These developments upset the traditional balance of power, creating a new dynamic in international relations and contributing to the complex tensions that led to the First World War.

=== The United States ===
The evolution of the United States between the end of the 18th century and the beginning of the 20th century is remarkable. The country went from being an isolated young nation to a world power. The great territorial expansion of the United States began in the early 19th century with the doctrine of "Manifest Destiny", a widely held belief that the United States was destined to expand across the North American continent. This ideology led to a series of territorial acquisitions, perhaps most notably the purchase of Louisiana from France in 1803, which doubled the size of the country. Other important territorial acquisitions include the purchase of Alaska from Russia in 1867 and the annexation of the Republic of Texas in 1845. At the same time as this territorial expansion, the United States experienced impressive demographic growth. Much of this population growth was due to immigration, with millions of people coming from Europe and elsewhere in search of a better life. Waves of immigration have also contributed to the diversity and vitality of American culture. Finally, the late nineteenth century ushered in the era of the 'Industrial Revolution', a period of rapid economic growth and technological innovation. The United States became a world leader in fields such as steel, oil and electricity, and major companies such as Standard Oil and Carnegie Steel dominated their respective sectors. All these factors, combined with a stable political system and a strong entrepreneurial spirit, enabled the United States to become a major global economic and military power at the dawn of the 20th century.

The rapid economic growth of the United States in the early 20th century was fuelled by a combination of factors, including the exploitation of vast natural resources, a large and increasingly skilled workforce, and major technological advances. The rapid industrialisation of the United States was supported by an abundance of natural resources, including coal, oil and various minerals, which provided the raw materials needed to fuel factories and machinery. In addition, a growing workforce - largely through immigration - provided the manpower to keep these industries running. The United States has also benefited from major technological and organisational advances. For example, Henry Ford's introduction of in-line assembly in the car industry revolutionised the manufacturing process and enabled goods to be produced more efficiently and at lower cost. As a result of this economic growth, the United States also gained in political influence. After the First World War, it became a major player on the international stage, playing a leading role in the formation of new international institutions such as the League of Nations, although it ultimately chose not to become a member. This influence grew even stronger after the Second World War, when the United States became one of the world's two superpowers, alongside the Soviet Union.

The territorial expansion of the United States was a major factor in its rise as a world power in the late nineteenth and early twentieth centuries:
* Alaska: The United States bought Alaska from Russia in 1867 for $7.2 million. This transaction, often referred to as "Seward's folly" after the Secretary of State William H. Seward who orchestrated it, added 1.5 million km² of territory to the United States. Alaska became the 49th US state in 1959.
* Hawaii: The Hawaiian Islands became a territory of the United States in 1898, following the revolution of 1893 that overthrew Queen Lili'uokalani. Hawaii was annexed mainly for economic and strategic reasons. It became the 50th state of the United States in 1959.
* Cuba, the Philippines and Puerto Rico: These territories were ceded to the United States by Spain at the end of the Spanish-American War in 1898 under the Treaty of Paris. However, Cuba was granted independence in 1902, although the United States retained certain rights of intervention and control of Guantanamo Bay. The Philippines gained independence in 1946, after the Second World War. Puerto Rico remained an unincorporated territory of the United States.

The foreign policy of President Theodore Roosevelt, who was in office from 1901 to 1909, played a key role in this development. His maxim, "Speak softly and carry a big stick", captures his foreign policy, often referred to as the "big stick policy". Roosevelt believed in peaceful engagement with other nations, but was prepared to use force, if necessary, to protect US interests. As part of this policy, Roosevelt worked to strengthen the US military presence, notably by sending the "Great White Fleet" on a world tour from 1907 to 1909 to demonstrate US naval power. He also used this approach in his management of the Panama Canal, the construction of which was a major achievement of his administration.

The territorial expansion of the United States at the end of the 19th century greatly contributed to its transformation into a world power. The acquisition of new territories and resources boosted the American economy, and the construction of naval bases in these territories extended the country's military reach. The aggressive foreign policies of presidents like Theodore Roosevelt also played an important role. Roosevelt, for example, supported the construction of the Panama Canal, which improved the United States' ability to project its naval power around the world. In addition, technological innovation and rapid industrialisation made the United States the world leader in industrial production in the early 20th century. These factors, combined with a rapidly growing population, gave the United States the means to exert its influence on a global scale. It is important to note that this rise to power was also accompanied by tensions and conflicts, both domestically and internationally. Ultimately, however, these developments laid the foundations for the United States' status as a superpower in the 20th century.

=== Japan ===
The Meiji era (1868-1912) in Japan was a period of profound and rapid transformation. Isolated for more than two centuries under the Tokugawa shogunate's policy of sakoku (national isolation), Japan was forced to open up to the outside world following the arrival of Commodore Matthew Perry's black ships from the United States in 1853. The Meiji Restoration in 1868 marked the start of a rapid process of modernisation and westernisation. The new government launched numerous reforms to modernise the country along Western lines, including the construction of modern infrastructure, the adoption of new technologies, the introduction of a universal education system, and the reorganisation of the army and navy along Western lines. These reforms transformed Japan from a feudal country into a modern industrial and military power in the space of a few decades. This enabled Japan to become the first non-Western power to defeat a modern Western power in the Russo-Japanese War of 1904-1905. This victory established Japan as a world power and changed the balance of power in East Asia.

In the late nineteenth and early twentieth centuries, Japan adopted an aggressive expansionist policy in East Asia and the Pacific. After the First Sino-Japanese War (1894-1895), Japan acquired Taiwan and the Pescadores Islands. Japan's victory over Russia in the Russo-Japanese War (1904-1905) not only established Japan as a world power, but also gave it control of Korea and certain territories in Manchuria. In 1910, Japan officially annexed Korea, which remained a Japanese colony until the end of the Second World War in 1945. During the First World War, Japan seized the opportunity to extend its influence in China and the Pacific. After the attack on Pearl Harbor in 1941 and for much of the Second World War, Japan controlled a vast empire that stretched across much of East Asia and the Pacific.

The Meiji Restoration, which began in 1868, marked a period of rapid modernisation and industrialisation in Japan. It was a time of great change, as the country moved from an isolated feudal system to a modern structure of governance and economy. These changes had a significant impact on Japan's position in the world. During this period, Japan also began to establish a colonial empire. The Sino-Japanese War of 1894-1895 marked an important stage in this expansion. Japan's victory and the resulting Treaty of Shimonoseki considerably increased Japan's influence in East Asia. Taiwan became a Japanese colony and Korea's independence was recognised, paving the way for increased Japanese influence and domination in the decades that followed. Japan's rapid modernisation, combined with its imperialist ambitions, saw the country rise to great power status in the late nineteenth and early twentieth centuries.

The Russo-Japanese War was a turning point not only in the history of Japan, but also in that of the world, challenging the unchallenged dominance of the European powers. Thanks to its rapid and effective modernisation, Japan was able to inflict a series of surprising defeats on Russia. Particularly significant was the decisive victory at the Battle of Tsushima, where the Russian fleet was virtually wiped out. The subsequent Treaty of Portsmouth recognised Japan's territorial gains in Korea and Manchuria. It marked the beginning of a new era in international relations, in which a non-European nation was able to take its place among the great powers. It also stimulated Japanese nationalism and strengthened Japan's position as a colonial power in Asia. However, it also sowed the seeds of future conflict, particularly with the United States, as a result of the expansion of Japanese influence in East Asia.

These developments in the early twentieth century marked the beginning of a profound shift in the global balance of power. While Europe was still at the centre of world affairs, the rise of the United States and Japan began to challenge this dominance. The United States, with its vast territory, growing population and ability to adopt and innovate in industrial technology, was able to surpass the European powers in many economic areas. Their influence was not limited to the economy: they also intervened significantly in the political affairs of Latin America and began to assert themselves as a major naval power. As for Japan, its rapid modernisation and victory over Russia not only transformed the country into a major regional power, but also challenged the conventional wisdom that European powers were militarily superior. This not only enhanced Japan's international status, but also set an example for other non-Western countries seeking to modernise. The rise of these two powers was one of many factors contributing to the growing instability in the run-up to the First World War, a period marked by increased tensions and rivalries between the great powers.

= The Era of Colonial Expansion =

The 19th century saw a significant increase in the size of colonial empires, particularly those of the European powers. In 1800, these empires controlled around 35% of the earth's surface, but this figure had risen to 85% by 1914. Colonial conquest was one of the major phenomena of the 19th century. Almost all the European powers embarked on this venture, and the consequences were considerable. The 19th century saw unprecedented colonial expansion, often referred to as the "New Imperialism". This phenomenon was largely driven by economic, political and strategic factors. Economically, the Industrial Revolution increased the demand of European powers for cheap raw materials and markets for their manufactured goods. The colonies offered not only valuable natural resources, but also captive markets for goods produced in Europe. Politically and strategically, the possession of vast colonial empires was seen as a sign of prestige and power. Rivalry between European powers often led to races to acquire and consolidate colonies, with each seeking to outdo the others. This often led to tension and conflict, including the Boer War in South Africa and the Fashoda Crisis in East Africa. 

At that time, imperialism and colonialism were major elements of the foreign policy of many world powers. The prevailing idea was that the most powerful nations had the right, indeed the duty, to extend their influence and control over weaker territories. This belief was often underpinned by notions of racial or cultural superiority, as well as a desire for economic gain. The British Empire, one of the largest in history, developed a complex administration to govern its many colonies. Britain also introduced many aspects of its culture and institutions into the territories it controlled, effects that persist to this day. Similarly, France established a vast colonial empire, particularly in Africa, where it imposed its language and culture. The natural resources of these colonies were exploited for the benefit of the metropolis. Germany, which was a more recent state in Europe, established several colonies in Africa and the Pacific, although its colonial empire was less extensive than those of France or Great Britain. Outside Europe, the United States and Japan became colonial powers in the late nineteenth and early twentieth centuries. The United States acquired territories such as the Philippines and Puerto Rico following the Spanish-American War, while Japan established an empire in East Asia, including Taiwan, Korea and parts of China.

Imperialism and colonialism are motivated not only by economic objectives, but also by political, strategic and symbolic aspirations. Politically and strategically, control of additional territories provided imperialist nations with additional military bases, trade routes and a greater ability to project their power on a global scale. Colonies could also act as buffers between the metropolis and potential enemies. On a symbolic level, owning colonies was often seen as a mark of greatness and prestige for a nation. It served to reinforce national sentiment and justify the political regime in power, by arguing that it was capable of obtaining and maintaining overseas colonies. The example of Germany is very relevant. As a recently unified country, Germany felt the need to demonstrate its power and legitimacy on the international stage. This led to a race to colonise and militarise, particularly in terms of building a powerful war fleet to rival that of Great Britain.

Colonisation was a major driver of nationalism in the colonising countries, partly because it reinforced a sense of national superiority and created a sense of common identity based on the domination of other peoples. The acquisition of foreign territories and resources was often presented as proof of a nation's greatness and power. In addition, colonisation created a sense of international competition between European powers, with each country seeking to outdo the others in terms of the number of colonies and territorial extent. It also fuelled nationalist sentiment, as citizens felt engaged in a global struggle for national supremacy. Finally, colonisation was often used to divert attention from domestic problems. For example, if a government faced social or economic unrest at home, it could launch a colonial campaign to divert public attention and create a sense of national unity. While colonisation strengthened nationalism in the colonising countries, it also sowed the seeds of nationalist movements among the colonised peoples. Faced with colonial oppression, many colonised peoples began to develop their own sense of national identity and to fight for independence.

== The Establishment of Colonial Empires==

=== The colonial empires ===
Colonisation has had devastating consequences for indigenous populations. In general, the colonisers sought to impose their own political, economic, social and cultural systems on the indigenous populations, often using force and repression. Indigenous cultures and languages were often suppressed, and colonised peoples were forced to adopt the colonisers' ways of life and beliefs. In addition, the natural resources of the colonies were exploited for the benefit of the economies of the colonising countries, often without regard to the needs or rights of the indigenous populations. Indigenous populations were often forced to work in extremely harsh conditions and exploited to extract these resources. Colonisation has also often led to deep and lasting inequalities. The colonisers generally established systems of segregation and discrimination, where indigenous people were considered inferior and deprived of many fundamental rights.

Natural resources were one of the main motivations for colonisation. The main objective of colonising countries was often to exploit the natural resources of the colonies to fuel their own economies. This could include resources such as gold and other precious metals, diamonds, rubber, spices, timber, tea, coffee, cotton and many others. To maximise the exploitation of these resources, colonising countries often set up administrative and labour systems that were extremely exploitative and oppressive for the local populations. These systems often included forced labour, land confiscation, taxation and other forms of economic exploitation.

King Leopold II of Belgium is known to have instituted a particularly brutal and exploitative regime in the independent state of Congo, which was his personal property and not a colony of Belgium. Leopold's regime forced the local population to harvest wild rubber under extremely difficult conditions. Those who failed to meet the quotas were often punished by mutilation or death. It is estimated that millions of people died as a result of the brutal working conditions and diseases associated with forced labour. In Indochina and Africa, France also exploited natural resources, including coal, copper, rubber and timber. Forced labour systems were also established, and local populations were often forced to work in extremely difficult conditions. Great Britain, for its part, heavily exploited the resources of India and its African colonies. In India, the cotton industry and tea plantations were among the main sectors exploited by the British.

Britain and France were the two greatest colonial powers of the 19th century in terms of the size and population of their respective empires.

The British Empire, often described as "the empire on which the sun never sets", was the largest. It spanned every continent, including territories as diverse as India, Australia, Canada, various parts of Africa, as well as many territories in the Caribbean and the Pacific.

The French Empire, although not as large as the British Empire, was also extensive and included territories in North Africa (notably Algeria, Tunisia and Morocco), sub-Saharan Africa (French West Africa and French Equatorial Africa), Asia (notably Indochina), as well as America and the Pacific.

Germany, Italy and Belgium were newcomers to the colonisation race and had smaller colonial empires. The German colonial empire included territories in Africa (Togo, Cameroon, South West Africa, East Africa) and the Pacific. Italy had colonies in Africa (Eritrea, Italian Somalia, Libya). Belgium, although small, controlled the enormous and richly endowed Congo.

Spain and Portugal, which had been leaders in exploration and colonisation in the 15th and 16th centuries, had smaller empires by the 19th century. Spain still controlled territories in Africa (Western Sahara, Equatorial Guinea) and the Pacific, while Portugal had colonies in Africa (Angola, Mozambique, Guinea-Bissau) and Asia (East Timor, Goa).

It should also be noted that Russia, although not generally considered a colonial power in the classical sense of the term, also underwent significant territorial expansion in the 19th century, particularly in Asia.[[File:Colonisation 1914.png|thumb|center|500px|The colonised world in 1914.]]

=== The British Empire ===
The British Empire was the largest in the world at its height, covering around 25% of the landmass and stretching across every part of the globe. The British Empire was truly a global empire, with territories on every continent. For more details: 

* In Asia, the British Empire controlled territories such as India (the "jewel in the crown"), modern-day Pakistan, Bangladesh, Malaysia, Singapore and Burma. India was particularly valuable to the Empire because of its wealth and population.
* In Africa, the British Empire controlled vast territories, including Egypt, Sudan, Kenya, Uganda, Zambia, Zimbabwe, South Africa and many others.
* In North America, even after losing the colonies that would become the United States, the British Empire retained Canada. The British also controlled territories in the Caribbean, such as Jamaica, the Bahamas and other islands.
* In Oceania, Australia and New Zealand were under British control, as were several Pacific islands.
* Even in Europe, the British controlled territories such as Malta and Cyprus, as well as strategic areas such as Gibraltar.

This vast empire enabled Britain to become a global superpower, with considerable cultural, economic, political and military influence.

The British Empire was made up of a variety of different territories, some of which were settlements, others exploitative colonies, and still others protectorates or mandates. 

* Settlements were generally territories where the British settled in large numbers, often because they were originally sparsely populated. These colonies often enjoyed a degree of political autonomy and were called dominions. Canada, Australia, New Zealand and South Africa were examples of such dominions.
* Exploitation colonies were territories that the British controlled primarily for their economic resources. These colonies were usually ruled by a governor appointed by the British monarch and often had a large indigenous population that was subject to British rule. Examples of such colonies include India, Burma, Nigeria and Sudan.
* Protectorates and mandates were territories that were not officially colonised by the British, but were under their protection or control. For example, Egypt and Sudan were protectorates, while Palestine and Transjordan were mandates conferred on Britain by the League of Nations after the First World War.

Each type of territory had a different status, and British laws and policies varied according to that status. However, in all these territories, the British exercised a degree of control and influence, whether through direct government, military protection or economic control.

The dominions of the British Empire gained greater autonomy during the nineteenth and early twentieth centuries, while remaining formally linked to Great Britain. This status enabled them to manage their own internal affairs while coordinating their foreign and defence policies with those of Great Britain. The Balfour Declaration of 1926 was a decisive moment in this development. It declared that the United Kingdom and its dominions were "equal in status, not subordinate to each other in any aspect of their internal or external affairs, though united by a common allegiance to the Crown, and freely associated as members of the British Commonwealth of Nations". This consolidated the principle that the Dominions were autonomous entities within the Empire, rather than subordinate possessions of Great Britain. Nevertheless, despite this formal declaration of equality, it remained true that the United Kingdom had a dominant influence over the foreign and defence policy of the Dominions, particularly until the Second World War. This was particularly evident in the First World War, when the Dominions were drawn into the conflict largely because of their link with Britain, although some Dominions such as Canada and Australia had a degree of autonomy in managing their war effort. 

Small islands were often of disproportionate strategic importance to colonial empires. Their usefulness as naval bases, supply stations or trading posts has often outweighed their size or population. The Pacific Ocean is a good example of this dynamic. Many colonial empires established colonies or protectorates on Pacific islands to serve as staging posts for ships bound for Asia or Australia. For example, the British Empire established colonies in Fiji and the Gilbert and Ellice Islands (now Kiribati and Tuvalu), while France established a protectorate over Tahiti and other islands in French Polynesia. The Indian Ocean also saw similar competition for strategic islands. The British Empire took control of Mauritius and the Seychelles, which were key naval bases on the route to India, while France established control over Reunion Island and Madagascar. In addition, some islands may have had valuable natural resources that were attractive to colonial empires. For example, the islands of the South Pacific were often rich in phosphate, an important resource for the fertiliser industry, while the islands of the Caribbean and the Indian Ocean had a climate conducive to the cultivation of products such as sugar, coffee and spices.

=== The French Empire ===
At the height of its expansion, the French Empire was the second largest colonial empire in the world in terms of surface area, after the British Empire. At its peak in the early 20th century, it covered around 11.5 million square kilometres, or almost 8.7% of the planet's land surface.

The empire spanned several continents, including large tracts of land in Africa, as well as possessions in Asia, America and the Pacific Ocean. In Africa, France controlled vast territories such as Algeria, Tunisia, Morocco, Mauritania, Mali, Niger, Chad, Senegal, Côte d'Ivoire and many others. In Asia, it possessed what we now call Vietnam, Laos and Cambodia, which were collectively known as French Indochina. In the Americas, France controlled Guadeloupe, Martinique, French Guiana and Saint-Pierre-et-Miquelon. The French Empire was culturally and linguistically diverse, with populations ranging from the Berbers of the Maghreb and the Vietnamese of Indochina to the Peuls and Wolofs of West Africa. However, this empire was also marked by strong tensions and conflicts, and many of its former colonies fought for their independence during the twentieth century.

The French Empire had a significant presence in Africa and Asia, with vast territories colonised in these regions. In Africa, French possessions stretched across the continent, including territories such as Algeria, Morocco, Tunisia, Senegal, Mali, Niger, Chad, Côte d'Ivoire, Gabon, Central African Republic, Congo, Djibouti and Madagascar, to name but a few. In Asia, French Indochina was a collection of territories including what is now Vietnam, Laos and Cambodia. France also maintained a presence in West Asia, with the mandate of Syria and Lebanon after the First World War. Finally, the French Empire also had colonies in the Pacific, notably New Caledonia and French Polynesia. The empire was therefore truly global, stretching across several continents and regions of the world.

In North Africa, Algeria was seen as an extension of France itself rather than a colony, a feature reflected in its designation as a French department. This meant that, unlike the traditional French colonies, Algeria was subject to the same laws as metropolitan France, although Muslim Algerians were institutionally discriminated against and did not enjoy the same rights as French citizens until the end of the Algerian War of Independence. France also had a significant influence on formally independent states such as Morocco and Tunisia through the protectorate system. Although these countries retained their own monarchs, France controlled their foreign policy and domestic administration. In South-East Asia, French Indochina included Vietnam, Laos and Cambodia, which were administered as colonies or protectorates. These regions were governed by French representatives, who imposed economic and social policies according to French interests. Other French colonies in Africa, such as Senegal, Mauritania, Mali, Niger and others, were also administered directly by France and were used for their natural resources and as markets for French goods.

=== The Dutch Empire ===
The Dutch Empire was an important colonial power, particularly during the 17th and 18th centuries, although its influence began to decline at the end of the 19th century.

Indonesia, then known as the Dutch East Indies, was the largest and most profitable colony for the Dutch. It comprised much of what is now Indonesia, including key areas such as Java, Sumatra and the Sunda Islands. The Dutch intensively exploited the resources of these islands, including spices, rubber, tin and oil. In addition to Indonesia, the Dutch also controlled various other territories. They maintained trading posts and colonies in other parts of Asia, notably Ceylon (now Sri Lanka) and Malacca. However, many of these possessions were lost to the British during the 18th and early 19th centuries. In America, New Amsterdam (now New York) was originally a Dutch colony, but was ceded to England in 1664. However, the Dutch maintained colonies in the Caribbean, notably Aruba, Bonaire and Curaçao, as well as Suriname in South America, which they retained until the 20th century. In Africa, the Dutch established a colony at the Cape of Good Hope (now in South Africa) in the 17th century, but it was conquered by the British in the 19th century. The Dutch also controlled territories on the west coast of Africa, such as present-day Ghana, where they established forts to support the slave trade, but these territories were sold to the British in the 19th century.

Indonesia, then known as the Dutch East Indies, was the Netherlands' most valuable colonial possession. It was administered by the Dutch East India Company (VOC) from the 17th century until the early 19th century, and then by the Dutch government itself. The Dutch colonial system in Indonesia was characterised by economic exploitation, political oppression and social inequality. The Dutch exploited the archipelago's rich natural resources, including spices, rubber, tin and oil, for the benefit of the metropolis. They also introduced a system of forced labour, known as the "cultuurstelsel" (cultivation system), which forced Indonesian peasants to grow export crops to the detriment of their own food crops. Politically, the Dutch maintained a strict colonial regime and suppressed any form of Indonesian resistance or nationalism. This created a profound social inequality, with a Dutch colonial elite at the top of the hierarchy and the majority of the Indonesian population living in poverty and destitution. This colonial system lasted until the Second World War, when Indonesia was occupied by Japan. After the war, Indonesia declared independence in 1945, but the Dutch tried to regain control by force. A war of independence ensued, which lasted until 1949, when the Dutch finally recognised Indonesia's independence.

Suriname, formerly known as Dutch Guiana, was a colony of the Netherlands for more than three centuries. Located in South America, it is bordered by Guyana to the west, Brazil to the south and east, and the Atlantic Ocean to the north. The colony's economy was largely based on agriculture, with sugar cane, coffee, cocoa and cotton plantations run by African slaves. The abolition of slavery in 1863 led to the importation of contract workers from India, Indonesia and China, helping to make Suriname a multi-ethnic and multicultural society. Suriname became an autonomous country of the Kingdom of the Netherlands in 1954, before becoming fully independent in 1975. Today, although Suriname is independent, historical links with the Netherlands remain strong, with a large Surinamese diaspora living in the Netherlands and Dutch as the country's official language.

=== The Belgian Empire ===
The independent state of Congo, now known as the Democratic Republic of Congo, was administered by King Leopold II of Belgium as his personal property from 1885 to 1908. Leopold was able to convince the other European powers to grant him control of the Congo at the Berlin Conference of 1884-1885, claiming that he wanted to promote civilisation and the eradication of slavery in the region. However, the reality was very different. The regime of Leopold II put in place a brutal system of economic exploitation, particularly of the rubber harvest. The people of the Congo were subjected to forced labour, and often mutilated or killed if they failed to meet the production quotas set. It is estimated that several million people died as a result of Leopold's exploitation of the Congo. In 1908, under international pressure following revelations of abuses committed in the Congo, the Belgian government took control of the territory, which became the Belgian Congo. Although some of the most brutal practices were abolished, Belgium continued to govern the Congo as a colony until its independence in 1960. The legacy of this period continues to have a profound impact on the Democratic Republic of Congo today.

Belgian Congo gained independence on 30 June 1960, becoming the Republic of Congo, also known as Congo-Léopoldville to distinguish it from neighbouring French Congo, now the Republic of Congo or Congo-Brazzaville. The transition to independence was marked by tension and conflict. The Congo had not been prepared for autonomy by the Belgian colonial authorities, who had not expected independence so quickly and had not planned accordingly. So, at the time of independence, there were very few Congolese trained to run the country's political and administrative institutions. After independence, the Congo was plunged into a series of political crises and conflicts, including the secession of the rich mining province of Katanga, the assassination of Prime Minister Patrice Lumumba, and the seizure of power by army commander Joseph Mobutu. Mobutu reigned as dictator for more than three decades, until he was overthrown in 1997. The country was then renamed the Democratic Republic of Congo.

=== The Portuguese Empire ===
The Portuguese colonial empire was one of the most enduring, beginning in the 15th century with the discovery of West Africa by Prince Henry the Navigator, and extending into the 20th century. In Asia, the Portuguese established trading posts in Goa, Diu and Daman in India, Malacca in Malaysia and Macao in China. These colonies were important centres for the trade in spices and other precious goods. Goa was the largest and most enduring colony in Asia, remaining under Portuguese control until 1961. In Africa, the Portuguese colonised areas that are now Mozambique and Angola. There they exploited slave plantations and other natural resources. In South America, Brazil was the most important colony of the Portuguese empire. The Portuguese began colonising Brazil in the early 16th century and it remained a Portuguese colony until its independence in 1822. During this period, the Portuguese exploited Brazil's rich natural resources, including precious woods, gold, diamonds and sugar cane.

The Portuguese Empire had colonies in Africa that included Angola, Mozambique, Guinea-Bissau (then known as Portuguese Guinea), Cape Verde, Sao Tome and Principe and parts of what is now Namibia. Angola and Mozambique were the Portuguese Empire's most important colonies in Africa. The Portuguese began exploring and colonising these regions in the 15th century. They established trading posts along the coast and eventually took control of vast territories inland, where they exploited natural resources and set up plantations using slave labour. Guinea-Bissau, Cape Verde and Sao Tome and Principe were smaller but important colonies for the Portuguese. They used them mainly as ports of call for their ships en route to other colonies in Africa, Asia and South America. Portugal's colonial rule over these territories lasted until the middle of the 20th century. National liberation movements led to wars of independence in these countries, which became independent in the 1970s.

=== The Italian Empire ===
Italy was one of the last European powers to take part in the partitioning of Africa. Its colonial empire was relatively small compared with those of Britain and France, but it did include significant territories. 

Eritrea and Italian Somalia (also known as Italian Somaliland) were Italian colonies on the east coast of Africa. Eritrea was the first colony to be acquired by Italy in 1890, while Somalia became a colony in 1908. These territories provided Italy with a strategic presence along the important trade route of the Suez Canal, as well as access to agricultural and mineral resources. Eritrea and Somalia provided Italy with a strategic position to control important trade routes along the Red Sea and the Indian Ocean. These colonies were also important for agriculture and the extraction of raw materials, which played an essential role in supplying the Italian economy. In Eritrea, the Italians built a network of railways and roads, as well as modern cities such as Asmara, which today is renowned for its Art Deco architecture. They also developed coffee and cotton plantations, exploiting the labour of the local population. In Somalia, the Italians also established agricultural plantations, mainly to produce bananas for export to Italy. The Italians also introduced new farming techniques and crops such as maize and citrus fruit.

Libya, on the other hand, was obtained as a result of the Italo-Turkish war of 1911-1912, during which Italy dislodged the Ottoman Empire from this territory. Libya was colonised as part of an effort to establish a "new Rome" in North Africa. Italy conquered Libya as part of the Italo-Turkish War, dislodging the Ottoman Empire from the territory. However, Italian control of Libya was far from peaceful. It was marked by intense local resistance, particularly during the Libyan War (1911-1932), which is often regarded as one of the longest and most costly colonial conflicts of the 20th century. Omar Mukhtar, a Libyan resistance leader, led a guerrilla campaign against the Italians. He succeeded in mobilising the tribes of the Cyrenaica region against the Italian occupation. Mukhtar was a skilled military strategist and managed to conduct effective guerrilla operations against the Italians for almost two decades. However, the Italians' military superiority, combined with their desire to crush the resistance at all costs, eventually led to Mukhtar's capture and execution in 1931. Libyan resistance continued for some time after his death, but the Italian occupation of Libya lasted until the Second World War, when Allied forces succeeded in expelling Italian and German forces from Libya. The Italian occupation had a profound impact on Libya, particularly in terms of its demography, economy and infrastructure. Italy encouraged the migration of Italian citizens to Libya, which changed the demographic composition of some parts of the country. The Italians also built roads, schools and other infrastructure, but they exploited Libya's resources for their own benefit.

These colonies remained under Italian control until the Second World War, when Allied forces dislodged the Italians from these territories. After the war, these territories became independent: Eritrea was initially annexed by Ethiopia before gaining independence in 1993, Somalia became independent in 1960, and Libya in 1951.

=== Russia ===
Russia's territorial expansion has been marked by a series of conquests and annexations of territories throughout its history. This expansion was often carried out by military means, and involved the integration of many different peoples and cultures into the Russian Empire. During the 19th century, Russia expanded eastwards into Asia and southwards into the Caucasus and Central Asia. This involved the conquest of vast territories, populated by many different ethnic groups. The consequences of this expansion are still visible today, particularly in the tensions that exist between the Russians and certain minority groups, such as the Chechens. Chechnya, located in the North Caucasus region, became part of the Russian Empire in 1859. However, relations between the Chechens and the Russian government have always been strained. The Chechens, with their distinct history, culture and religion, have often resisted Russian rule, and there have been several attempts at secession over the years.

In 1867, Russia sold Alaska to the United States for $7.2 million, a deal known as the 'Alaska Purchase'. At the time, some Russians criticised the sale, believing that Russia was abandoning a potentially valuable territory. However, Alaska was at the time a remote and difficult territory for Russia to administer. From the American point of view, the purchase of Alaska proved extremely beneficial in the long term. Alaska is rich in natural resources, including oil, natural gas, gold and fish. The discovery of gold in the territory at the end of the 19th century triggered a gold rush, and in the 20th century Alaska became a major source of oil for the United States. So although the Alaska Purchase was initially derided as "Seward's folly" (named after the US Secretary of State William H. Seward who orchestrated the deal), it is now generally regarded as an excellent deal for the US.

=== Japan ===
Both Japan and the United States established colonial empires from the nineteenth century onwards, although their colonial approach and ideology differed from those of European empires. Japan, having modernised and industrialised following the Meiji era, began looking for territories to colonise at the end of the nineteenth century. Taiwan and Korea became Japanese colonies in 1895 and 1910 respectively. Japan's colonial expansion continued in the 1930s and 1940s, with the invasion of Manchuria, China and various territories in the South Pacific. The United States, meanwhile, began acquiring colonies following the Spanish-American War of 1898. It gained control of Puerto Rico, Guam and the Philippines as a result of this war, and also annexed Hawaii in 1898. The United States also exercised control over other territories, such as Samoa and the Virgin Islands. However, the American ideology of "manifest destiny" and democratic traditions often created a tension between colonial objectives and national ideals.

The Meiji era in Japan, which began in 1868 and ended in 1912, was a period of rapid and radical modernisation. The Meiji government sought to establish Japan as a modern industrialised nation capable of competing with the Western powers. These modernisation efforts included massive political reform, the adoption of Western industrial technologies, the establishment of a Westernised education system, and the development of a modern army and navy. One of the main motivations behind these reforms was Japan's desire to avoid the fate of many other Asian countries that had been colonised or dominated by Western powers. Japan saw what was happening to countries like China and India and decided to adopt a policy of assimilation and adaptation of key aspects of Western culture, technology and organisation, rather than resistance. This enabled Japan not only to avoid colonisation, but also to become a colonial power itself. In 1895, Japan won the first Sino-Japanese war, which marked the beginning of Japanese imperialism in Asia. As a result, Japan acquired Taiwan and the Pescadores Islands. Later, in 1910, Japan annexed Korea, making it a colony. During the first half of the 20th century, Japan continued to expand its empire, occupying part of China (Manchuria) and many territories in the Pacific during the Second World War.

Japan began its imperialist policy with the annexation of the island of Taiwan in 1895 following victory in the Sino-Japanese War. Japan then acquired new colonies in Asia, notably Korea in 1910, as well as territories in the Pacific and China during the Second World War. In 1895, following the First Sino-Japanese War, Japan acquired Taiwan and the Pescadores Islands of China, marking the beginning of its imperial expansion. In 1905, following the Russo-Japanese War, Japan gained further territory, including China's Liaodong Peninsula (which includes Port Arthur, a major naval base) and Sakhalin Island to the north. It was the first time an Asian nation had won a major victory over a European power, and it radically changed the balance of power in the region. In 1910, Japan officially annexed Korea, ending the Joseon dynasty and establishing colonial rule. Japanese control of Korea was particularly brutal, with many cases of forced labour, cultural repression and other human rights abuses. In the 1930s and 1940s, Japan continued its expansion into China, including the invasion of Manchuria in 1931 and the establishment of a puppet state called "Manchukuo". This led to wider conflicts with China and eventually to Japan's entry into the Second World War. During the Second World War, Japan conquered large areas of the Pacific and South East Asia, including the Philippines, Indonesia, Malaysia, Singapore and much of Burma. However, these territorial gains were lost when Japan surrendered to the Allies in 1945.

Japan's colonial empire was dismantled at the end of the Second World War, and the country was forced to relinquish all its overseas territories under the Treaty of San Francisco in 1951.

=== The United States ===
After independence, the United States pursued a policy of territorial expansion on its own continent, known as "Manifest Destiny". This policy held that the United States was destined to expand from coast to coast across the North American continent. This led to the annexation of vast tracts of land, including the Louisiana Territory in 1803, Florida in 1819, Texas in 1845 and the south-western territories following the Mexican-American War of 1846-1848. However, it was towards the end of the 19th century that the United States began to establish colonies outside its continent, adopting a form of imperialist policy. This was fuelled by various factors, including the desire for new economic opportunities, the need to establish military bases abroad in support of the Monroe Doctrine (which aimed to prevent interference by European powers in the affairs of the Americas) and the influence of certain ideologies, such as Social Darwinism.

The Spanish-American War of 1898 led the United States to acquire several Spanish territories, including the Philippines, Puerto Rico, Guam and Cuba. These acquisitions marked a break with past US policy, which had focused primarily on expansion in North America. The annexation of these territories provoked heated debate in the United States. Some Americans, including many members of the Anti-Imperialist Party, condemned these actions as contrary to the democratic and anti-colonial principles on which the nation had been founded. However, others, such as President Theodore Roosevelt, supported expansion as a demonstration of national greatness and a means of competing with European empires on the world stage. The US also annexed Alaska (bought from Russia in 1867) and Hawaii (which became a US territory in 1898 after the Hawaiian monarchy was overthrown by American settlers in 1893).

After the Second World War, the United States began to distance itself from traditional colonialism and chose to promote its influence through economic and political means rather than through the direct occupation of foreign territories. This was done in the context of decolonisation, as many former colonies gained their independence. That said, the US continued to maintain certain territorial possessions, such as Puerto Rico, Guam, the Northern Mariana Islands, the US Virgin Islands, and the remote minor island in the Pacific Ocean. Although these territories are not colonies in the traditional sense of the term, they remain under US sovereignty and their inhabitants are US citizens. However, they do not enjoy all the same rights as citizens residing in the 50 States - for example, they cannot vote in presidential elections unless they reside in one of the States. Furthermore, American strategy in the twentieth century evolved to become more economic and diplomatic, with a strong emphasis on trade agreements, financial aid, political and military alliances, and the promotion of democracy and human rights. These strategies helped establish the United States as a global superpower, despite the decline of its colonial empire.

== Rivalry and competition: the Race for Colonies ==

The aspiration to conquer new territories gave rise to intense rivalry between different colonial powers. In their quest to extend their sphere of influence and domination, the colonial powers targeted the most strategic and richest territories. This gave rise to a veritable "race for colonies" from the second half of the nineteenth century to the beginning of the twentieth, involving major European powers such as France, the United Kingdom, Germany, Italy and Portugal, as well as Japan and the United States. Their expansion was often at the expense of the indigenous populations of these territories. 

Africa became a particularly hotbed of this competition, as the colonial powers sought to appropriate the continent's abundant natural wealth, including raw materials such as rubber, diamonds, gold and oil. Colonial rivalry helped inflame tensions and provoke major conflicts, such as the Boer War in South Africa (1899-1902), triggered by the dispute between the United Kingdom and Boer settlers over control of gold and diamond mines; or the Italo-Ethiopian War (1935-1936), when Mussolini's fascist Italy invaded Ethiopia, one of the few African countries to have resisted European colonisation, in a bid for national prestige and a desire to control Ethiopia's resources; and the Franco-Tunisian War (1881), which led to the establishment of a French protectorate over Tunisia, motivated by security concerns and economic interests in Tunisia, such as olive oil, wheat and mining.

In addition, competition between these great powers was a contributing factor to the outbreak of the First World War, with colonial issues exacerbating tensions between European nations.

== The Berlin Conference: Partition of Africa ==

[[File:Kongokonferenz.jpg|thumb|right|300px|Representation of the Berlin Conference (1884), attended by representatives of the European powers.]]

The Berlin Conference, also known as the West Africa Conference, was held from November 1884 to February 1885 in Berlin, Germany. The meeting was intended to ease tensions and resolve problems arising from colonial rivalries among the various European powers. The main objective was to divide Africa into zones of influence and territories to be colonised, thus defining the rules of the game for the Race to Africa. 

The conference, initiated by German Chancellor Otto von Bismarck, brought together 14 nations, including all the major European powers of the time, as well as the United States. During the conference, the participants drew up regulations concerning the annexation of African territories, stipulating that any territorial claim had to be notified to the other powers and that the claiming power had to occupy the territory concerned. This conference had a major impact on the history of Africa, leading to the arbitrary drawing of borders and the division of the continent between the European powers. This partition, which largely ignored existing ethnic and cultural realities in Africa, had long-term consequences for the continent's political, social and economic development.

The decisions taken at the Berlin Conference catalysed the colonisation of Africa by the European powers. By establishing rules for the division of Africa, the conference paved the way for the accelerated occupation and annexation of the continent. After the conference, the map of Africa began to resemble a patchwork of colonies controlled by different European powers. For example, France took control of large areas of West and Central Africa, the United Kingdom extended its hold over East and Southern Africa, while other countries such as Germany, Portugal, Italy and Belgium also acquired important territories.

Otto von Bismarck, as German Chancellor, had a dual objective at the Berlin Conference. On the one hand, he sought to ease tensions with France, which was still unhappy about the loss of Alsace-Lorraine as a result of the Franco-Prussian War. Bismarck hoped that supporting French colonial expansion in North Africa would distract France from its desire to retake Alsace-Lorraine. On the other hand, Bismarck's ambition was to strengthen the international status of the newly unified Germany. He wanted Germany to be recognised as a legitimate colonial power by the other European nations. So, at the Berlin Conference, Germany laid claim to several territories in Africa, including Togo and Cameroon in West Africa, as well as German South-West Africa (present-day Namibia) and German East Africa (comprising parts of present-day Burundi, Rwanda and Tanzania). Bismarck had some success in achieving these goals.

The Berlin Conference established a framework for the organisation of the colonisation of Africa, delimiting the zones of influence of the various European colonial powers on the African continent. However, this major historical event also amplified the rivalries between these same powers. Colonial greed led to tensions and conflicts between the various nations, particularly as they expanded into newly acquired territories. For example, intense competition crystallised between Great Britain and France in North Africa, with Egypt and Sudan the main stakes. Similarly, antagonism between Great Britain and Russia manifested itself in clashes in Central Asia, particularly around Afghanistan. Germany and France also expressed their colonial rivalry in West Africa, where they battled for control of Togo and Cameroon. These colonial rivalries created a climate of uncertainty and tension in Europe, a precarious atmosphere that eventually led to the outbreak of the First World War. Colonial conflicts soured relations between the European powers, dragging them into an all-out war for control of colonial territories. This historical context shows the extent to which colonial issues were a determining factor in the international tensions that led to the outbreak of the Great War.

== The Impact of the Colonisation of Africa ==

[[Fichier:Egypt sudan under british control.jpg|thumb|British Egypt and Sudan. This 1912 map shows the site of Fachoda (Kodok) to the south, on the Nile.]]

At the dawn of the 18th century, the vast majority of African regions were governed by autonomous political entities, each with its own distinct cultures, languages and political systems. While Europeans had succeeded in establishing trading posts and coastal colonies, most of the interior of the continent remained largely inaccessible to their influence. Over the years, however, the European powers gradually increased their presence in Africa. Their means of asserting their influence on the continent were varied, ranging from military force to the imposition of political and economic controls. This gradually transformed the political map of Africa as the European powers expanded their colonial empires.

In Africa, the colonial powers also found themselves competing to extend their territories. The official start of the colonisation of Africa by these European powers was recorded at the Berlin Conference of 1884-1885. This meeting led to an arbitrary division of the African continent between European nations, with no regard for the traditional borders or distinct cultures of the various African ethnic groups. The rivalries that resulted from this partition led to several armed conflicts for control of specific regions of Africa. For example, the Boer War in South Africa pitted the British against the Afrikaners, descendants of Dutch settlers, for control of the gold and diamond mines. Similarly, the Italian-Ethiopian War of 1895-1896 was sparked by Italy's colonial ambitions in Ethiopia, one of the few African nations that had resisted European colonisation. These conflicts illustrated the brutality of colonial competition, with lasting repercussions on African societies.

As well as using military force, the European powers also employed indirect methods to increase their hold on Africa. For example, they signed treaties with local rulers, established protectorates and created zones of influence. Although these methods may have seemed more subtle, they still resulted in a loss of sovereignty for the people of Africa. The impact of colonisation on these populations was devastating. Africans were dispossessed of their land and natural resources. In addition, European settlers often exploited the African workforce, forcing them to work in difficult conditions and for derisory pay. In addition, colonisation often led to the suppression of local cultures and traditions. Europeans sought to impose their own culture, language and religious beliefs, thus contributing to the erosion of African cultural identities.

At the beginning of the twentieth century, Africa had been divided up between the European powers, defining specific zones of influence for each of them. However, this division did not put an end to rivalries and tensions, and conflicts continued to erupt over control of certain regions. These ongoing power struggles reflect the intensity of colonial ambition at the time, as each nation sought to maximise its control and influence over the African continent.

Britain and France, as the dominant colonial powers, sought to expand their sphere of influence in Africa during the nineteenth century. Over time, the British Empire consolidated its hold on territories such as Egypt, Sudan, South Africa, Southern Rhodesia (now Zimbabwe) and various parts of East Africa. For its part, France extended its hold in West Africa, encompassing Senegal, Mali, Côte d'Ivoire, Niger, Burkina Faso and Guinea, as well as in Central Africa with Chad and Congo-Brazzaville, not forgetting East Africa with Djibouti and French Somalia.

One of the most notable illustrations of the rivalry between these two great colonial powers was the Fachoda crisis in 1898. This episode saw France and Great Britain squabbling over control of the Upper Nile region, an area of major strategic importance. Despite the risk of escalating into armed conflict, the situation was eventually resolved peacefully through diplomatic compromise, underlining the importance of negotiations in settling colonial disputes.

France's colonisation of Tunisia in 1881 raised tensions with Italy, which also had colonial ambitions for the territory. Italy, with a large community of Italians living in Tunisia at the time and significant commercial interests, hoped to use Tunisia as an extension of its sphere of influence in North Africa. France's success was therefore perceived by Italy as a missed opportunity, fuelling a rivalry between the two nations. This tension was a contributing factor in Italy's subsequent quest for colonial expansion in Africa, notably with the conquest of Libya in 1911 and Ethiopia in the 1930s under Mussolini.

Under Kaiser Wilhelm II, Germany adopted a policy of colonial expansion and rivalry with the other European powers, particularly Britain and France. This policy, known as Weltpolitik, aimed to make Germany a world power on a par with its competitors. The Moroccan crisis of 1905-1906, also known as the First Moroccan Crisis, is a clear example of these colonial tensions. Germany opposed French control over Morocco, putting forward the principle of free trade and challenging France's dominance over the territory. However, at the Algeciras conference in 1906, which aimed to resolve the crisis, the majority of the participating countries supported France's position, thus isolating Germany. This conflict not only exacerbated tensions between Germany and France, but also highlighted the rivalries between the European powers for control of colonial territories. It also led to a strengthening of the Entente Cordiale between France and Great Britain, as they sought to thwart Germany's colonial ambitions.

== The dismantling of the Ottoman Empire ==
During the 19th century, the Ottoman Empire, nicknamed "the sick man of Europe", was in constant decline, weakened by a series of internal problems such as economic difficulties, ethnic tensions and religious conflicts. As a result, European powers, including Britain, France and Russia, sought to take advantage of this weakness to increase their influence in the territories of the Empire.

The Crimean War (1853-1856) is a clear example. This conflict pitted Russia against a coalition comprising the Ottoman Empire, the United Kingdom, France and the Kingdom of Sardinia. One of the underlying reasons for the conflict was the struggle for control of the Holy Places of Christianity in the Holy Land, then under Ottoman control. The conflict revealed the military weakness of the Ottoman Empire and the interest of the major European powers in dismantling it. In Central Asia, the rivalry between Russia and the United Kingdom, known as the "Great Game", centred on control of Afghanistan and the surrounding regions. Both powers feared that an advance by the other would offer a strategic advantage in the region. Tensions came to a head during the Second Anglo-Afghan War (1878-1880), when the UK sought to counter Russian influence by establishing a favourable regime in Kabul. At the same time, the Russo-Turkish War of 1877-1878 demonstrated the Ottoman Empire's inability to resist a Russian invasion. The Treaty of San Stefano that ended the war was largely in Russia's favour, which alarmed the other major powers and led to a revision of the treaty at the Congress of Berlin in 1878. These geopolitical rivalries not only exacerbated tensions between the great European powers, but also triggered a series of wars and conflicts in the territories of the Ottoman Empire, the consequences of which helped to shape the Middle East and the Balkans as we know them today.

Several factors contributed to this situation, including the rise of European power, the Industrial Revolution, internal conflicts, wars and revolts. The Industrial Revolution, which began in the 18th century in Britain before spreading to Europe and beyond, created a great disparity in economic and military power. European countries were able to use their industrial advantage to build powerful armies and fleets, and were able to establish colonial empires across the world. Meanwhile, the Ottoman Empire remained largely agrarian and feudal, with no significant industrial capacity. Internally, the Ottoman Empire was also plagued by problems. Uprisings broke out across the empire, such as the Serbian uprising of 1804-1815, the Greek War of Independence of 1821-1830, and the Bulgarian, Armenian and Arab revolts later in the 19th century. These uprisings not only drained the empire's resources, but also exposed its weakness to the outside world. Moreover, military defeats, such as in the Russo-Turkish War of 1877-1878, weakened the Ottoman Empire's international position. As a result, the great European powers, such as Great Britain, France, Russia, and later Germany and Italy, began to compete for influence over the Ottoman Empire. This led to what is often referred to as the "Eastern Question" - a diplomatic debate about how the European powers should deal with the decline of the Ottoman Empire. This created a complex web of alliances and rivalries between the European powers, contributing to the international tension that eventually led to the First World War. The Ottoman Empire subsequently collapsed after its defeat in the First World War, and the modern Republic of Turkey was founded in 1923.

The Balkan Wars were an intense conflict that led to a major redistribution of power in the Balkan region.

The Ottoman Empire lost much of its territory in the Balkans to the Balkan states of Bulgaria, Serbia, Montenegro and Greece, which had allied themselves in the First Balkan War (1912-1913) against the Ottoman Empire. However, these allies soon quarrelled over the division of the conquered territories, triggering the Second Balkan War (1913) in which Bulgaria fought its former allies and eventually lost part of the territory it had won in the first war. The Balkan Wars exposed the Ottoman Empire's military weaknesses and showed that the Ottoman Empire was in rapid decline. They also created instability and tension in the Balkan region, which eventually escalated into the First World War. After the First World War, the Ottoman Empire was completely dismantled, and its remaining territories were divided between the victorious Allied Powers, mainly Great Britain and France, under the terms of the 1920 Treaty of Sèvres. These powers created mandates to administer the territories, creating Syria and Lebanon under the French mandate, and Iraq and Palestine under the British mandate. This division of the Middle East had lasting consequences for the region, some of which are still felt today.

The Italo-Turkish War of 1911-1912, also known as the Tripolitan War, marked an important stage in the disintegration of the Ottoman Empire. Italy was seeking to assert itself as a colonial power and saw Ottoman Libya (then known as Tripolitania and Cyrenaica) as an opportunity to do so. The Ottoman Empire, already weakened and having problems controlling its vast territories, was unable to effectively resist the Italian invasion. The war was finally resolved by the Treaty of Lausanne (1912), which confirmed Italy's annexation of Libya. Italy also took control of the Dodecanese islands in the Aegean Sea. This was a major defeat for the Ottoman Empire and a further sign of its decline. The loss of Libya not only weakened the Ottoman Empire, but also shifted the balance of power in the Mediterranean in Italy's favour. It would be one of many territorial losses for the Ottoman Empire over the next two decades.

The discovery of vast oil reserves in the Middle East played a significant role in the international politics of the early twentieth century. Oil was identified as a strategically vital resource for the economy and security of industrialised nations, and obtaining and controlling its supply became a major foreign policy objective for many powers. The major European powers, particularly Britain and France, sought to establish control and influence over oil-producing regions such as Persia (modern Iran) and Iraq. Control of these regions was essential to fuel their economies and naval fleets. This led to new rivalries and tensions as nations fought over control of oil-rich areas. For example, the Sykes-Picot Agreement of 1916, which divided the Middle East between France and Britain, was largely motivated by the desire to control access to oil resources.

Despite its natural resources, including oil, the Ottoman Empire failed to modernise sufficiently to compete with the great European powers in the late 19th and early 20th centuries. Its inability to implement effective reforms, corruption, mismanagement and political instability contributed to its economic and military decline. The discovery of oil transformed the geopolitics of the region. The great powers, in particular Great Britain and France, realised very early on the strategic importance of oil for warfare and industrialisation. They therefore sought to secure access to these resources, either through direct colonisation or through protectorates and agreements with local leaders. For example, the British Anglo-Persian Oil Company (which later became BP) obtained a concession to explore for oil in Persia (modern-day Iran) in 1901. Later, the French company Compagnie française des pétroles (now Total) obtained exploration rights in the Middle East following the Sykes-Picot Agreement in 1916. These developments not only exacerbated rivalries between the great European powers, they also accelerated the decline of the Ottoman Empire and contributed to the rising tensions that led to the First World War. It also had a lasting impact on the region, which remained at the centre of international conflicts over the control of oil throughout the twentieth century.

== The Stakes of the Far East ==
The Far East was an area of major imperial rivalry, particularly at the turn of the 20th century. Russia's growing influence in the region, particularly in Manchuria and Korea, was of concern to Britain and Japan. Russia sought to secure access to the Pacific Ocean, which would give it an independent eastern route out of the often frozen Arctic route. Britain, for its part, saw Russian expansionism in Central Asia as a threat to its own interests in India, the "jewel in the crown" of the British Empire. As for China, it had been the object of the appetite of the colonial powers since the mid-nineteenth century. Great Britain had imposed unequal treaties on China following the Opium Wars, giving it access to the Chinese market. France, Germany, Russia and Japan subsequently obtained similar concessions. Japan, for its part, was seeking to become an imperialist power in its own right. Its victory over Russia in the Russo-Japanese War of 1904-1905 was a key moment, enabling it to establish its dominance in Korea and strengthen its presence in Manchuria. These rivalries in the Far East contributed to the rise in international tensions at the beginning of the 20th century. They also had a lasting impact on the region, contributing to the emergence of conflicts such as the Russo-Japanese War, the First and Second World Wars, and the subsequent conflicts in Korea and Vietnam.

The Russo-Japanese War of 1904-1905 had major international implications. One of the most significant consequences was the reorganisation of the balance of power in the Far East. Until then, Russia had been perceived as a major force in the region. Its defeat at the hands of Japan, a non-Western country that had modernised with impressive speed since the Meiji Restoration in 1868, took the world by surprise. It showed for the first time that a non-European power could defeat a major European power in a major military conflict. Japan emerged from the war with an enhanced status, being recognised as a major world power. It gained control of Korea (which it officially annexed in 1910) and the Russian territory of Port Arthur in Manchuria. In addition, Japan's victory had an impact on non-Western colonies and countries around the world. It stimulated nationalist movements in several Asian countries, notably India and China, which saw Japan's victory as proof that resistance against Western imperialism was possible. However, the Russo-Japanese war also led to an escalation of tensions in the Far East. Japan's rise to power created anxiety among the other colonial powers, notably the United States, and laid the foundations for other conflicts in the region, including the Second World War in the Asia-Pacific.

The geopolitical situation in Afghanistan was marked by the "Great Game", an intense strategic and political rivalry between the British Empire and the Russian Empire for control of Central Asia in the 19th century. Afghanistan, with its strategic geographical position, was seen by the British as an essential bulwark for the protection of their colonial jewel, India. The Russians, for their part, saw Afghanistan as a potential stage in their expansion to the south and east. The Second Anglo-Afghan War (1878-1880) was a direct consequence of these rivalries. The British, fearing growing Russian influence on the Afghan regime, invaded Afghanistan in 1878. After a series of battles, the Treaty of Gandamak was signed in 1879, guaranteeing Afghanistan a degree of autonomy while bringing its foreign policy under British control. These events had a lasting impact on Afghanistan and the surrounding region. They contributed to a long period of instability and conflict in the country, and defined Afghanistan's role as a contested zone of influence within the wider framework of international rivalries. Subsequently, the involvement of the great powers in the region persisted throughout the twentieth century and into the twenty-first, with significant consequences for the history of Afghanistan.

In the 19th century, the Western powers used their military superiority to force China to open up to their commercial activities. The unequal treaties, which were highly disadvantageous to China, granted the foreign powers numerous rights, including the establishment of concessions where they exercised extraterritorial jurisdiction, the opening up of numerous ports to international trade, and costly war indemnities. The Opium War, triggered by China's refusal to allow the opium trade, led to the first series of unequal treaties, most notably the Treaty of Nanking in 1842, which not only forced China to legalise the opium trade, but also ceded Hong Kong to the British and opened several ports to foreign trade. The Sino-Japanese War of 1894-1895 marked the rise of Japan as a colonial power. China was forced to recognise the independence of Korea, previously a Chinese tributary, and to cede Taiwan and the Pescadores Islands to Japan. The Boxer Rebellion, an anti-Western rebellion, was crushed by an alliance of eight foreign nations, further strengthening their influence and control over China. These events not only weakened the Qing dynasty and exacerbated China's internal problems, but also caused a national humiliation that had a lasting impact on China's collective consciousness. This ultimately contributed to the emergence of modern nationalism in China and the fall of the Qing dynasty in 1911.

South America was seen as a kind of exclusion zone for European powers because of the Monroe Doctrine, which was a policy of the US administration to prevent European powers from interfering in the affairs of the Western Hemisphere. In enunciating the Monroe Doctrine in 1823, President James Monroe declared that the United States would regard any European intervention in the affairs of America's independent nations as an unfriendly act against the United States. This doctrine served as the basis for US foreign policy in Latin America for over a century and has been invoked on several occasions to justify US intervention in regional affairs. By contrast, in other parts of the world, such as Africa, Asia and the Pacific, the European powers have been much more active in establishing colonies and spheres of influence, often at the expense of local populations. This has often led to conflicts and rivalries between these powers, which have been a major source of instability and international tension.

= Establishing Alliance Systems =
At the beginning of the 20th century, the alliance system played a crucial role in the development of the international political situation. The emergence of the Triple Entente and the Triple Alliance created a political and military polarisation in Europe, with two blocs of powers facing each other. The Triple Entente, formed by France, Russia and the United Kingdom, sought to counter the perceived threat of the Triple Alliance, made up of Germany, Austria-Hungary and Italy. However, it is important to note that Italy had a somewhat ambiguous position, having signed a secret alliance with France in 1902. The system of alliances intensified rivalries between these powers and contributed to an atmosphere of mistrust and suspicion. Each side sought to strengthen its own military capabilities to protect itself against possible aggression from the other. In addition, colonial disputes and imperialist ambitions also fuelled tensions between these powers. Ultimately, these rising tensions led to the First World War in 1914, when the assassination of Archduke Franz Ferdinand of Austria in Sarajevo triggered a series of events that dragged most of the major European powers into the conflict.

The alliance system played a major role in the expansion of the First World War. When a conflict broke out between a Triple Entente power and a Triple Alliance power, it quickly led to the involvement of all the powers of both alliances. The assassination of Archduke Franz Ferdinand of Austria in June 1914 by a Serbian nationalist served as the detonator. Austria-Hungary, supported by Germany, declared war on Serbia. Russia, Serbia's ally, then went to war against Austria-Hungary. France and the United Kingdom, Russia's allies in the Triple Entente, soon declared war on Germany and Austria-Hungary. Italy, despite its membership of the Triple Alliance, chose to remain neutral before joining the Entente in 1915. Other countries, such as the Ottoman Empire (allied with Germany) and Japan (allied with the United Kingdom), also became involved in the conflict. In 1917, the United States entered the war on the side of the Entente. The war quickly became a global conflict, making the First World War one of the most destructive wars in history. Millions of people were killed and many parts of the world were ravaged.

== The Role and Impact of the Triple Alliance ==
[[File:Triple Alliance.png|thumb|right|Triple Alliance|La Triple Alliance entre l'Allemagne, l'Autriche-Hongrie et l'Italie.]]

The term "duplicity" is used to refer to the alliance between Germany and Austria-Hungary that existed before the First World War.

The Three Emperors Alliance, which included Germany, Austria-Hungary and Russia, was signed in 1873. However, this alliance was not renewed in 1887 due to growing disputes between Russia and Austria-Hungary. In 1879, Germany and Austria-Hungary formed the Duplice, a secret alliance aimed at countering Russia's growing influence in Eastern Europe. Italy joined this alliance in 1882, creating the Triple Alliance. The Treaty of Reassurance, signed in 1887, was a separate agreement between Germany and Russia. This agreement helped to maintain peace between the two countries, despite their belonging to different alliance systems. However, this treaty was not renewed in 1890, which eventually led to estrangement between Russia and Germany and an approach between Russia and France, culminating in the formation of the Franco-Russian Alliance in 1894.

The alliance between Germany and Austria-Hungary, known as the Duplice, was signed in 1879. The alliance was partly born out of a shared fear of Russian expansion in Europe. Both were worried about the possibility of war on two fronts: Germany feared a confrontation with France and Russia, while Austria-Hungary was concerned about Russia and Italy. By entering into this alliance, they hoped to discourage such a situation. In 1882, Italy joined the alliance, which then became the Triple Alliance. Italy was motivated by the fear of French expansion in North Africa and sought the support of Germany and Austria-Hungary for its own colonial ambitions. However, it should be noted that Italy's commitment to the alliance was less solid, as Italy had unresolved territorial claims against Austria-Hungary. When the First World War broke out, Italy initially declared its neutrality, before joining the Allies in 1915 following the signing of the Pact of London, which promised Italy territorial gains after the war.

The 1881 agreement uniting Germany, Austria-Hungary and Russia failed to last, due to divergent interests between the three nations. Russia, which saw itself as the protector of the Slavic peoples in the Balkans, came into conflict with the ambitions of Austria-Hungary, which aspired to hegemony in the same region. Faced with this impasse, a new pact was formed in 1882, this time between Germany, Austria-Hungary and Italy, giving rise to the Triple Alliance. This treaty was intended to counterbalance the Triple Entente, an alliance made up of France, Russia and Great Britain. It also stipulated that each signatory would provide military support to the others in the event of external aggression.

Italy's entry into the Triple Alliance marked an important milestone in the country's history, as it was the first time it had participated in such a collective security agreement with major European powers. Italy, newly unified and relatively weak compared to other great powers, was looking for powerful allies to protect its interests, and Germany and Austria-Hungary offered that security. Moreover, Italy's membership of the Triple Alliance was part of a wider strategy of colonial expansion. At the end of the nineteenth century, Italy was seeking to establish its own colonial empire, mainly in North Africa. Tunisia, just across the Mediterranean from Sicily, was a particularly attractive target for Italy. However, France also had its eye on Tunisia, which led to tensions with Italy. Therefore, by joining the Triple Alliance, Italy hoped to gain the support of Germany and Austria-Hungary to counter French influence in Tunisia and other parts of North Africa. However, Italy's colonial ambitions in North Africa met with considerable resistance, particularly from France, and led to tensions within the Alliance.

Italy was part of the Triple Alliance with Germany and Austria-Hungary, but its participation in the alliance was complex and fraught with contradictions. In 1882, Italy had joined the Triple Alliance in an attempt to protect itself against possible French aggression and to gain support for its colonial ambitions. However, Italy also had many differences with its allies, in particular with Austria-Hungary, which controlled territories that Italy considered to be part of its "irredent Italy", notably Trentino and South Tyrol. At the start of the First World War, Italy chose to remain neutral, arguing that the Triple Alliance was essentially a defensive alliance, and that since Austria-Hungary had been the aggressor by declaring war on Serbia, Italy was not obliged to support it. Italy was subsequently lured to the side of the Triple Entente (France, the United Kingdom and Russia), which promised significant territorial gains in Austria-Hungary as part of the London Accords of 1915. When Italy entered the war on the side of the Triple Entente in May 1915, it marked a major reversal of alliances in Europe and further widened the scope of the war. It also showed how alliances could be subject to rapid change depending on circumstances and perceived opportunities.

The First World War was fought between two major blocs: the Central Powers and the Triple Entente. The Central Powers, sometimes referred to as the Central Empires, consisted mainly of the German Empire, the Austro-Hungarian Empire and, initially, the Kingdom of Italy. However, as discussed earlier, Italy left this alliance in 1915 to join the side of the Triple Entente. Other notable members of the Central Powers were the Ottoman Empire and the Kingdom of Bulgaria. The Triple Entente was formed by the French Republic, the United Kingdom and the Russian Empire. As the war progressed, other nations, including Italy, Japan and the United States, joined their cause. The resulting conflict was a total war that involved not only military forces but also civilian populations, and had repercussions on every aspect of society. It also led to the fall of the German, Austro-Hungarian, Russian and Ottoman empires, and redrawn the political map of Europe and the Middle East.

== The Formation and Influence of the Triple Entente ==
[[File:Triple Entente.jpg|thumb|200px|alt=Triple Entente.jpg]]

Although the Triple Entente was not a formal military alliance like the Triple Alliance, it did serve to unite France, Russia and the United Kingdom against the threat of the Central Powers. The Entente Cordiale between France and the United Kingdom in 1904 improved relations between the two countries, which had historically been fraught with colonial rivalries. This agreement mainly resolved colonial disputes in North Africa, leading to greater cooperation between the two nations. At the same time, France and Russia signed a series of agreements between 1891 and 1894, culminating in the Franco-Russian Alliance. These agreements included a mutual assistance clause in the event of an attack by Germany or one of its allies. The United Kingdom, having resolved its colonial differences with France and watched the German threat grow, signed an agreement with Russia in 1907, known as the Anglo-Russian Convention. This agreement resolved their differences in Central Asia and strengthened anti-German sentiment among the three countries. These agreements helped to create a climate of mutual trust and cooperation between the three countries, strengthening their ability to respond collectively to the threat from the Central Powers.

The Franco-Russian Alliance, concluded in 1892 and officially ratified in 1894, was an essential pivot in the foreign policy of these two countries. Indeed, it was of vital importance in the run-up to the First World War. Economically, the alliance was beneficial to both sides. France was a major investor in Russia, providing financial support for the country's industrial and railway development. In return, Russia offered a vast market for French goods and services. On the military front, the treaty stipulated mutual assistance in the event of an attack by Germany or one of its allies. This provision reflected growing concerns about Germany's growing power in the European context. Diplomatically, the alliance helped to break France's international isolation following its defeat in the Franco-Prussian War of 1870-1871. For Russia, the alliance brought it closer to Western Europe. The Franco-Russian alliance was renewed in 1899 and continued until the First World War, when it played a key role in the outbreak of the conflict.

The Entente Cordiale of 1904 marked a key stage in the improvement of relations between France and the United Kingdom, putting an end to centuries of colonial rivalry and mistrust. The UK's recognition of France's sphere of influence in Morocco and France's recognition of the UK's sphere of influence in Egypt was a major step in consolidating this new friendly relationship. In 1907, the Entente Cordiale was extended with the addition of Russia, forming the Triple Entente. This agreement between Russia and the United Kingdom was designed to resolve their differences in Central Asia and Persia. It also provided for cooperation in the event of aggression by Germany or Austria-Hungary against one of the signatories. This series of agreements thus created a solid alliance between these three major powers, which ultimately played a key role in the outbreak of the First World War. The main objective of this alliance was to counter the growing threat posed by Germany and Austria-Hungary in the European context of the time. The Triple Entente therefore comprised France, Russia and the United Kingdom, and was directed against Germany and the Austro-Hungarian Empire.

The Anglo-Russian agreement of 1907 represented a major turning point in relations between the United Kingdom and Russia, two powers that had had major disputes in the Far East, particularly over Iran, Afghanistan and Tibet. These territories were seen as strategic buffers by the British, who wanted to protect their colonial jewel, India, from Russian ambitions. Under this agreement, the two countries succeeded in establishing zones of influence in Iran, recognised the independence of Afghanistan and agreed not to intervene in Tibet. The British recognised Russian political and economic interests in Iran, while the Russians undertook not to interfere with British interests in India. The easing of tensions between Russia and the United Kingdom paved the way for the formation of the Triple Entente, which also included France. This alliance was fundamental to the balance of power in Europe on the eve of the First World War.

Great Britain and Japan concluded a naval agreement in 1902, known as the Anglo-Japanese Alliance. This agreement was motivated by the desire of these two powers to stem Russian expansion in the Far East, more specifically in the region of Manchuria and Korea. Under the terms of the agreement, if either party was at war with two or more powers, the other party would have to come to its aid. In addition, each party undertook to remain neutral if the other was at war with another power. The renewal of the Anglo-Japanese Alliance in 1905 and 1911 marked an important stage in Britain's foreign policy in the Far East, as it not only strengthened its position in the region, but also weakened Russia. The agreement also played a crucial role in the Russo-Japanese War of 1904-1905, in which Japan emerged victorious, strengthening its position in Asia and asserting its status as a world power.

The existence of these alliances played a major role in the escalation of tensions at the beginning of the 20th century. The mutual obligation to defend one's allies created a kind of constant pressure and tension, where every aggressive act or political move was scrutinised through the prism of these alliances. This pressure led to an arms race and military escalation that paved the way for the First World War. The situation was further complicated by the complex and sometimes secretive nature of these alliances. For example, the outbreak of the First World War was largely caused by the assassination of Archduke Franz Ferdinand of Austria in Sarajevo in 1914. Because of its alliance obligations with Austria-Hungary, Germany declared war on Russia and France. This set off a chain reaction, with each country declaring war on those who threatened their allies, ultimately leading to a world war. This situation was also exacerbated by the bellicose and expansionist attitude of certain powers, notably Germany. Feeling that it had the support of its allies, Germany adopted an aggressive foreign policy, which helped to increase tensions. So the alliance systems, while intended to preserve peace by ensuring a balance of power, actually contributed to the escalation of tensions and ultimately led to war.

= The First World War: The Suicide of Europe =

The First World War is considered to be one of the deadliest conflicts in history, with an unprecedented scale of destruction. The conflict began with the assassination of Archduke Franz Ferdinand of Austria-Hungary in Sarajevo in June 1914, an event that triggered a series of military mobilisations and declarations of war between the major European powers due to their respective systems of alliances. The United Kingdom, France and Russia formed the Allies, also known as the Triple Entente. Other nations, including Italy, Japan and, later, the United States, joined the Allies during the war. On the other hand, Germany, Austria-Hungary and the Ottoman Empire formed the Central Empires, sometimes referred to as the Central Powers. These two blocs fought on several fronts, including the Western Front in France and Belgium, the Eastern Front in Russia, and several other fronts in Italy, the Balkans and the Middle East. The war was characterised by trench warfare, a military tactic where both sides fought from fortified trenches and where advances were often measured in metres despite massive casualties. The war also saw the use of new technologies and weapons, including heavy artillery, aircraft, tanks, submarines and poison gas. These innovations contributed to the massive loss of life and destruction of civilian infrastructure. The First World War ended on 11 November 1918 with the signing of the armistice. The consequences of the conflict were profound, with the redrawing of the map of Europe, the collapse of the central empires, the emergence of new states and the establishment of the Treaty of Versailles, which laid the foundations for the Second World War a few decades later.

The assassination of Archduke Franz Ferdinand on 28 June 1914 is often cited as the event that sparked off the First World War. However, it was not the assassination itself that caused the war, but rather the way in which different nations reacted to the event. Austria-Hungary, having been assured of German support, declared war on Serbia, accused of complicity in the assassination. Russia, which saw itself as the protector of the Slavic peoples, including the Serbs, began to mobilise its army in support of Serbia. Germany, as an ally of Austria-Hungary, declared war on Russia and subsequently on France, Russia's ally. When Germany invaded Belgium to attack France from the north, the violation of Belgian neutrality led the United Kingdom to declare war on Germany. Other countries were drawn into the conflict because of their respective alliances or their own imperialist interests, turning the war into a global conflict. The conflict lasted from 1914 to 1918, involving more than 30 nations and causing the deaths of millions of people. It radically transformed the political and social order of the world and laid the foundations for the tensions and conflicts that dominated the twentieth century.

The consequences of the First World War were profoundly destructive and transformed the world in an unprecedented way. The loss of life was enormous: around 10 million soldiers were killed and millions more were wounded. The number of civilians killed or injured as a direct result of the war is difficult to quantify, but is estimated to be in the millions. The Spanish flu epidemic of 1918, aggravated by the displacement of populations during the war, also caused the deaths of tens of millions of people around the world. Beyond the human losses, the economic and social costs of the war were enormous. European countries, in particular, saw their infrastructures destroyed and their economies ruined. War debts burdened economies for decades. Societies were also profoundly disrupted: millions of people were displaced, political regimes were overthrown and old social hierarchies were challenged. Politically, the war led to the end of the great European empires (Russian, German, Ottoman and Austro-Hungarian) and the creation of new nations, redrawing the map of Europe and the Middle East. In addition, the Treaty of Versailles, which officially ended the war in 1919, created tensions and resentments, particularly in Germany, which contributed to the rise of fascism and ultimately to the Second World War. Finally, the First World War also had profound cultural and psychological consequences. It called into question the ideals of progress and civilisation that had prevailed before the war, and led to a reconsideration of reason and morality.

Perhaps the most striking features of the First World War were trench warfare and the intensive use of new military technologies. Trench warfare was a defensive strategy in which both sides dug and occupied a complex network of trenches, hoping to protect their troops while blocking the enemy's advance. Living conditions in these trenches were atrocious: cold, rain, mud, vermin, disease, and the constant danger of enemy fire and artillery attacks. In addition, offensives to take control of enemy trenches were often disastrous, causing huge casualties for minimal territorial gains. The battles of the Somme and Verdun, among the deadliest in human history, are perfect examples of these disastrous offensives. The First World War also saw the use of new military technologies on an unprecedented scale. Artillery was improved, with the introduction of the fragmentation shell and the massive use of heavy artillery. Machine guns, tanks, military aircraft, submarines and even chemical weapons were used on a large scale for the first time. These technological innovations helped to increase the lethality of the conflict, but they also led to a war of attrition, with each side trying to exhaust the other through massive losses rather than decisive victories. Ultimately, the First World War revealed the true horror of modern industrial warfare, with its millions of dead, devastated landscapes and lasting psychological trauma.

The First World War had a major geopolitical impact, redrawing the map of Europe and the Middle East. The collapse of the central empires led to the creation of many new states. The Treaty of Versailles, which officially ended the war, imposed severe sanctions on Germany and redrawn the borders of Europe. The German Empire was dismantled, losing much of its territory to the victors. The Austro-Hungarian Empire was divided into several nation states, including Austria, Hungary, Czechoslovakia and Yugoslavia. The Ottoman Empire, defeated and occupied, was divided between the victorious powers with the Treaty of Sèvres in 1920, leading to the creation of new states in the Middle East, such as Iraq and Syria. However, the resistance led by Mustafa Kemal Atatürk in Turkey led to the Turkish War of Independence and the creation of the modern Republic of Turkey. In Russia, the collapse of the Eastern Front led to the Russian Revolution of 1917, which overthrew the Tsarist regime and established a Communist government, leading to the creation of the Soviet Union. These radical changes destabilised the political and social order in Europe and the Middle East. Tensions between the new states and unresolved grievances from the war contributed to the rise of authoritarian and fascist regimes, ultimately leading to the Second World War.

== Escalating tensions: Preamble to the Conflict ==
The run-up to the First World War was marked by a series of international crises and local conflicts that exacerbated tensions between the major European powers and undermined the stability of the international system at the time. The first Moroccan crisis in 1905-1906 arose when Germany challenged France's ambitions in Morocco, causing international tension that was resolved by the Algeciras Conference. This conference resulted in an agreement that recognised Morocco as a free state but confirmed France's effective control over the country, which was seen as a defeat for Germany. Italy's invasion of Libya in 1911 marked an escalation in international tensions. Libya was then a province of the Ottoman Empire, and the Italian invasion triggered an international crisis because of the implications for the balance of power in the Mediterranean and the Middle East. The Balkan Wars of 1912-1913 further exacerbated tensions. They were triggered by a series of conflicts between several Balkan states (Serbia, Bulgaria, Greece and Montenegro) and the Ottoman Empire. These wars challenged the balance of power in the region and created a climate of mistrust and animosity, particularly between Serbia and Austria-Hungary. These crises not only exacerbated the rivalries between the great powers, but also highlighted the weaknesses of the alliance system of the time and the limits of diplomatic mechanisms for resolving conflicts. They helped to create a climate of tension and mistrust that eventually led to the outbreak of the First World War in 1914. 

The twentieth century began with a series of international crises that exacerbated tensions between the great European powers. Colonial, economic and military rivalries led to an arms race and an increasing polarisation of international politics, with two major alliance blocs emerging. The Triple Alliance, formed by Germany, Austria-Hungary and Italy, and the Triple Entente, formed by France, the United Kingdom and Russia, were strengthened by the accession of other countries. Bulgaria, disappointed by the outcome of the Balkan wars, chose to ally itself with the Triple Alliance. On the other hand, Greece, which had benefited from these wars to expand its territory, drew closer to the Triple Entente. The complexity and interconnectedness of these alliances not only crystallised oppositions, but also created a climate of uncertainty and mistrust that ultimately led to the outbreak of the First World War. The alliances forced countries to support each other in the event of war, even if the reasons for the conflict were not always clear or directly linked to their interests. In addition, the arms race raised the stakes and created an atmosphere of tension and anticipation of inevitable war.

== From Local Crisis to the Flame of European War ==

=== The Assassination of Archduke Franz Ferdinand: The Initial Fuse ===
The attack that took place in Sarajevo on 28 June 1914 is widely recognised as the catalyst that plunged the world into the First World War. On that day, Archduke Franz Ferdinand, the heir apparent to the Austro-Hungarian throne, was tragically killed in Sarajevo, the capital of Bosnia-Herzegovina, by Gavrilo Princip, a young Serb nationalist. Born on 25 July 1894 in Obljaj, then part of the Bosnian province of the Austro-Hungarian Empire and now in Bosnia-Herzegovina, Princip was a fervent supporter of Serbian nationalism. He is best known for the tragic assassination of Franz Ferdinand in Sarajevo. An active member of the "Black Hand", a clandestine organisation advocating the independence of Bosnia-Herzegovina and its integration into Serbia, Princip had undergone military training in Serbia before returning to Bosnia to orchestrate the attack. On the fateful day, 28 June 1914, Princip, along with several other members of the Black Hand, managed to approach Archduke Franz Ferdinand's car during his visit to Sarajevo. He then shot the Archduke and his wife, Sophie, with a pistol. This set off a chain reaction of alliances and reprisals that led to military escalation and, ultimately, the outbreak of the First World War. After the attack, Princip was arrested and imprisoned. Tried for his role in the assassination of the Archduke, he was sentenced to 20 years in prison. However, he did not have to serve the full sentence, dying in prison in 1918, aged just 23, of tuberculosis.

The Sarajevo bombing triggered a cascade of diplomatic and military reactions that led to war in Europe. After the assassination of Archduke Franz Ferdinand, Austria-Hungary pointed the finger at Serbia, accusing it of having orchestrated the crime, and demanded reparations. This accusation was not unfounded. Since the 1870s and 1880s, Serbia had been a thorn in the side of the Austro-Hungarian Empire. At that time, Serbia had embarked on a campaign to unify the Slavic peoples of the southern Balkans, a region that included populations under Austro-Hungarian rule. This unification movement was perceived by the Austro-Hungarian Empire as a direct threat to its territorial integrity and stability. Fear that their empire would disintegrate as a result of the rise of Slav nationalism prompted the Austro-Hungarian rulers to take retaliatory measures against Serbia after the assassination of the Archduke. This tension between the two nations was one of the main triggers for the escalation that led to the First World War.

The annexation of Bosnia-Herzegovina by Austria-Hungary in 1908 aggravated tensions with Serbia. This province, under Austro-Hungarian protectorate since the Congress of Berlin in 1878, was mainly populated by South Slavs, an ethnic group to which the Serbs also belonged. The Serbs aspired to the integration of these regions into a "Greater Serbia", an idea fuelled by the current of Panslavism. The official annexation of Bosnia-Herzegovina by Austria-Hungary was perceived by Serbia as a violation of their national ambitions. Moreover, the annexation was seen as a direct threat to Serbia, as it gave Austria-Hungary a common border with the kingdom. In response, Serbia increased its support for the nationalist movements active in the Austro-Hungarian regions populated by South Slavs, further exacerbating tensions with the Austro-Hungarian Empire. These growing tensions played a crucial role in the outbreak of the First World War.

The assassination of Archduke Franz Ferdinand in 1914 by Gavrilo Princip, a Serbian nationalist, set off a firestorm in an already tense Europe. Perceived by Austria-Hungary as a direct affront, this act triggered an ultimatum to Serbia, demanding reparations and guarantees. However, Serbia refused to comply fully with Austro-Hungarian demands, prompting Austria-Hungary's declaration of war on Serbia on 28 July 1914. The complex system of military alliances between the great European powers quickly transformed this regional conflict into a global conflagration. Germany, linked to Austria-Hungary by the Triple Alliance, declared war on Russia and France, Serbia's allies. Similarly, the Ottoman Empire and Bulgaria, with their own agreements with Germany and Austria-Hungary, went to war against the Allies - the United Kingdom, France, Russia, Italy, Japan and later the United States. Thus began the First World War, a large-scale conflict that reshaped the world as we know it.

The assassination of Archduke Franz Ferdinand was merely the spark that ignited a powder keg prepared by years of simmering tensions. The breeding ground for the First World War was much deeper and more complex, rooted in a series of interconnected factors. Nationalism, for example, was a major factor. In many parts of Europe, particularly the Balkans and parts of the Austro-Hungarian Empire, nationalist movements sought to create unified nation states for their peoples. This nationalism was sometimes accompanied by anti-imperialist sentiments and a desire for freedom from foreign domination. Imperialism also played a crucial role. The great European powers were engaged in a race for colonial expansion throughout the world, which exacerbated rivalries and tensions between them. Competition for resources, markets and prestige created a climate of mistrust and animosity. Finally, internal economic and political tensions also contributed to the march towards war. Rapid economic change exacerbated inequalities and social tensions in many countries, while rigid political structures often failed to respond to demands for reform. Although the assassination of Franz Ferdinand was the immediate catalyst for the war, its root causes were deeply rooted in the social, political and economic structures of the time.[[fichier:Frontouest1914gf.gif|right|thumb|350px|The Western Front between 1915 and 1916 - [http://www.atlas-historique.net/1914-1945/cartes/FrontOuest1915-16.html atlas-historique.net]]]

=== Chronology of the events of the First World War ===
The fateful act of 28 June 1914 in Sarajevo, when Archduke Franz Ferdinand of Austria-Hungary was assassinated, is widely recognised as the trigger for the First World War. This dramatic event triggered an international crisis with fatal consequences, exacerbating already existing tensions between the European powers and provoking a cascade of military and political alliances that ultimately plunged the world into global conflict. Gavrilo Princip, the young man who carried out the assassination, was a fervent Serbian nationalist. His convictions were so deep that he had forged links with the secret radical group known as the Black Hand. This terrorist group, whose aim was the liberation of the southern Slavs from Austro-Hungarian rule, was the catalyst that enabled Princip to carry out his destructive act.

The assassination of Archduke Franz Ferdinand led Austria-Hungary to issue a stern ultimatum to Serbia on 23 July 1914. This ultimatum demanded a thorough investigation into possible Serbian involvement in the assassination, as well as the cessation of all hostile activities against Austria-Hungary on Serbian soil.

Although Serbia agreed to the majority of these demands, it refused to comply with all of Austria-Hungary's requests. This led Austria-Hungary to declare war on Serbia on 28 July 1914, triggering a series of events that rapidly amplified existing tensions and activated the networks of alliances between the various powers, ultimately leading to the global outbreak of the First World War. Following Austria-Hungary's declaration of war on Serbia on 28 July 1914, alliances were formed and one country after another declared war on another. Germany declared war on Russia on 1 August 1914, then on France the following day, prompting the United Kingdom to enter the war in support of France. Many other countries subsequently joined the conflict, including Italy, Japan, the United States and the Ottoman Empire. By mid-August 1914, most of the major European powers were involved in the conflict.

After declaring war on France on 3 August 1914, Germany launched a rapid offensive through Belgium, aimed at neutralising France before potential reinforcements arrived. However, this lightning advance was halted by the resistance of French and British forces, culminating in the Battle of the Marne, which took place from 6 to 12 September 1914. This battle was one of the most significant confrontations of the First World War. It enabled the Allies to effectively repel the German forces and prevent the capture of Paris. However, contrary to initial expectations of a short war, the conflict became bogged down and lasted four more years, with a catastrophic human and material toll.

After the Battle of the Marne in September 1914, despite their desire to advance towards Germany, the French and British forces faced determined resistance from the German armies. The Germans succeeded in withdrawing and fortifying themselves in strategic defensive positions stretching from the North Sea through Belgium and France to the Swiss border. What followed was a "race to the sea", where each side tried to bypass the other from the west. However, this strategy eventually led to the construction of a network of trenches to consolidate and protect the positions acquired. This scenario marked the beginning of trench warfare, which lasted for several years, symbolising the stagnation and deadlock of the conflict on the Western Front.

In December 1914, the war's Western Front stretched from the English Channel to the German border, a 700-kilometre stretch through northern France and Belgium. Both belligerents entrenched themselves in impenetrable trench positions, turning the conflict into a series of static and deadly face-offs. Nevertheless, efforts were still being made to break the deadlock. Although massive offensives often resulted in huge losses without much territorial gain, the hope of a decisive breakthrough never completely faded. This fierce fighting on the Western Front continued until the end of the war in 1918.

From December 1914 until the end of the conflict in November 1918, the belligerents were mired in trench warfare. This type of warfare was characterised by networks of deep, fortified trenches protected by barbed wire and heavy weapons. These trenches, often only a few dozen metres apart, became the scene of incessant fighting. Much of the military activity consisted of assaults on enemy trenches, intensive artillery bombardment and carefully planned large-scale offensives, all with the aim of breaking through the enemy lines. These attempts often resulted in minimal gains of territory at the cost of considerable loss of life. This war of position, emblematic of the First World War, entailed colossal human and material costs on both sides. The trenches, symbols of this stalemate and of the futility of war, have left their mark on our memories and have gone down in history as testimony to the carnage of that era.

The trench warfare that raged on the Western Front between 1915 and 1918 during the First World War was marked by unprecedented brutality. Soldiers on both sides of the conflict were forced to live in appalling conditions, confined to cramped, unhealthy trenches, exposed to bad weather and disease, and under constant artillery fire. They were also subject to toxic gas attacks, air raids, machine-gun fire and bayonet assaults. The slaughter was immense: millions of lives, both military and civilian, were lost, and countless others were wounded, traumatised or displaced by the fighting. The war also left an indelible mark on the psyche of the survivors, with many soldiers suffering from war trauma, psychiatric disorders and eating disorders. The scale of the devastation, both physical and psychological, had a profound effect on the societies affected, leaving a lasting legacy of pain and loss. The horror and inhumanity of trench warfare became symbols of the futility and absurdity of war in general.

The Battle of Verdun and the Somme Offensive, which took place in 1916, were among the most devastating battles of the First World War. These battles are regarded as emblematic examples of the brutality and massive loss of life characteristic of trench warfare. The Battle of Verdun began on 21 February 1916 with a German offensive. The German forces hoped to exhaust the French army by forcing it to defend the fortified town of Verdun. The battle lasted until 18 December 1916, making it one of the longest in history. It was marked by fierce fighting, massive bombardments, the use of poison gas and enormous loss of life. It is estimated that there were around 800,000 casualties, many of whom died in terrible conditions. The Somme Offensive began on 1 July 1916, with the aim of relieving pressure on the French forces at Verdun and weakening the German army. British and French forces launched an offensive along a 40km front in northern France. The first day of the offensive was the deadliest in the history of the British Army, with around 57,000 casualties. The offensive, which lasted until November, claimed more than a million casualties on both sides. These battles have left a deep imprint on our collective memory because of their violence and the scale of the loss of life. They contributed to making 1916 one of the deadliest years of the First World War.

The Chemin des Dames Offensive, also known as the Second Battle of the Aisne, took place in April 1917. It was orchestrated by French General Robert Nivelle, who had promised a decisive victory over the Germans in 48 hours thanks to an innovative artillery strategy and rapid movement. However, the preparations for the offensive were well known and the German forces were well prepared to resist it. The offensive began on 16 April 1917 and was immediately met with strong resistance. The French soldiers came up against reinforced and well-prepared German defences, incessant machine-gun fire and unfavourable weather conditions. In addition, the French artillery was unable to effectively eliminate the German defences before the attack. Instead of the promised quick victory, the offensive turned into a costly stalemate that lasted until 9 May 1917, with few territorial gains to show for it and catastrophic casualties. French losses were estimated at around 187,000 men, and German losses at around 168,000. This devastating defeat had a significant impact on the morale of French troops, leading to large-scale mutinies in the French army. The political consequences of this failure were just as significant. Nivelle was quickly removed as commander-in-chief and replaced by General Philippe Pétain, who had to work hard to restore morale in the French army. This event marked a turning point in the way the war was fought by the French, with a shift to a more defensive and cautious strategy.

The entry of the United States into the war in April 1917 provided valuable support to the Allies. When the United States entered the war, it was an economically robust nation and had a large potential population of soldiers. Although their regular army was small and inexperienced, they were able to mobilise quickly and send large numbers of troops to Europe. The American contribution was essential in both material and human terms. Economically, the United States provided significant financial support to the Allies, enabling them to maintain their war effort. The United States also provided large quantities of supplies, equipment and munitions, which helped the Allies maintain their numerical superiority over the Axis forces. In human terms, the arrival of the American Expeditionary Forces (AEF), led by General John J. Pershing, strengthened the Allied forces on the Western Front. American troops took part in several major offensives in 1918, helping to turn the tide of the war. However, although America's entry into the war had a significant impact, it came relatively late in the conflict and was not the decisive factor in the Allied victory. Previous battles, fought mainly by French, British and Russian forces, had considerably weakened the central forces even before the Americans arrived on the front.

The final year of the First World War, 1918, saw a major shift in the balance of power. After years of trench warfare and attrition, the Allied forces were able to launch several successful offensives that finally forced Germany to capitulate. After signing the Treaty of Brest-Litovsk with Russia in March 1918, Germany launched a series of massive offensives on the Western Front, known as the Spring Offensives. However, although these offensives initially met with some success, they failed to break the Allied line decisively and cost Germany many precious lives. The Allied forces launched a series of counter-offensives, the most famous being the Second Battle of the Marne in July 1918. This battle marked the beginning of the end for German forces on the Western Front. Subsequently, the Allies launched the Hundred Days Offensive, a series of attacks that gradually pushed the German forces back from their positions. The Meuse-Argonne offensive, in which American forces played a significant part, was a key part of this campaign. Meanwhile, Germany was plagued by internal unrest, including strikes, mutinies and civil unrest, exacerbated by food shortages caused by the British naval blockade. Against this backdrop, Germany asked for an armistice, which was signed on 11 November 1918, putting an end to the fighting on the Western Front. This armistice marked the end of the First World War, although the final terms of the peace were not fixed until the Treaty of Versailles the following year.

11 November 1918 marked the official end of hostilities in the First World War. This day became known as Armistice Day and is commemorated every year in many countries. The armistice was signed in a train carriage in the forest of Compiègne in France. The terms of the armistice required, among other things, that the Germans evacuate the occupied territories, surrender a significant amount of artillery and other military equipment, and allow certain areas of Germany to be occupied by the Allies. After the armistice was signed, peace negotiations began in Paris. These negotiations culminated in the signing of the Treaty of Versailles in June 1919. This treaty placed the responsibility for the war on Germany and its allies and demanded from them considerable reparations, territorial concessions and disarmament. The harsh terms of the treaty were a source of controversy and resentment in Germany, contributing to the tensions that eventually led to the Second World War.

Russia, as a member of the Triple Entente with France and the UK, played an important role in the war. However, Russia faced many difficulties during the war. The defeat at the Battle of Tannenberg was a major setback for the Russian army and marked a turning point in the war on the Eastern Front. Over the next few years, Russia continued to struggle against the central forces, but was weakened by internal problems, including growing dissatisfaction with the war, economic mismanagement and political instability. These problems culminated in 1917 with the February and October Revolutions. The February Revolution overthrew Tsar Nicholas II and established a provisional government, while the October Revolution brought the Bolsheviks to power. After taking control, the Bolsheviks quickly began peace negotiations with Germany, which led to the signing of the Treaty of Brest-Litovsk in March 1918. This treaty officially ended Russia's participation in the First World War. However, Russia's exit from the war had major consequences for the Allies, as it allowed Germany to concentrate all its forces on the Western Front. However, this situation was eventually offset by the entry of the United States into the war in April 1917, which helped to redress the balance of power.

The Balkans were a theatre of particularly intense confrontation during the First World War. Romania, with a majority of its population of Latin language and culture, joined the Triple Entente, composed mainly of France, the United Kingdom and Russia, in the hope of recovering Romanian-populated territories that were then under the control of the Austro-Hungarian Empire. However, the Romanian offensive was halted by the forces of the Central Empires (Germany, Austria-Hungary and their allies) and Romania was occupied until the end of 1918, when the collapse of the Central Empires allowed Romania to recover and even expand its territory. Serbia, meanwhile, was a key player in the outbreak of war with the assassination of Archduke Franz Ferdinand of Austria in Sarajevo in June 1914. Serbia resisted the Austrian offensives in 1914, but was invaded and occupied in 1915 by the forces of the Central Empires. However, with the help of French and British forces who had landed at Salonika in Greece, Serbia managed to regain control of its territory during the Allied counter-offensive in 1918, contributing to the collapse of Austria-Hungary and the eventual Allied victory. It is also important to note the role played by other Balkan nations during the war. Bulgaria, for example, aligned itself with the Central Empires, hoping to recover the territories lost in previous Balkan wars, but was ultimately defeated and suffered significant territorial losses in the Treaty of Neuilly-sur-Seine in 1919. Similarly, Greece, after a period of neutrality and internal tensions, joined the Allies in 1917 and played an important role in the Balkan operations.

Russia has historically had ambitions to expand southwards, in particular to secure year-round access to ice-free water. The Bosphorus and Dardanelles Straits, which link the Black Sea to the Mediterranean, were of major strategic importance to Russia as they were the only sea passage for Russian ships from the Black Sea to the rest of the world. In addition, Russia presented itself as the protector of the Slavs and Orthodox Christians in the Balkans, which led to tensions with the Ottoman Empire, which controlled a large part of the region. This played a part in Russia's involvement in the First World War alongside Serbia and other Slavic countries in the Balkans. The war against the Ottoman Empire proved difficult for Russia. The war effort was complicated by internal problems, including social and political tensions that eventually led to the Russian Revolution and the collapse of the Tsarist regime. After the revolution, the new Communist government sought to end the war. Under the Treaty of Brest-Litovsk in 1918, Russia renounced its claims to the straits in exchange for an end to hostilities with the Central Powers, which included the Ottoman Empire.[[fichier:fronts1418.jpg|center|thumb|350px|Fronts of the First World War.]]

== The Globalisation of Conflict: International Actors ==
The First World War was a world war in the sense that it involved nations from all over the world. The European colonial empires played an important role in the conflict, providing troops, resources and sometimes additional theatres of war. The First World War was a global conflict, involving nations from all over the world. The European colonial empires played an important role in the conflict, mobilising their colonies to provide troops and resources, and sometimes even serving as additional theatres of war. The British Empire mobilised many countries for the conflict. Nations such as India, Canada, Australia, New Zealand and South Africa sent troops to fight alongside the British. In particular, India provided almost 1.5 million soldiers who served in Europe, Africa and the Middle East. Similarly, France mobilised troops from its colonies, with soldiers coming from regions such as Algeria, Morocco, Tunisia, sub-Saharan Africa and Indochina. Germany used its colonies mainly for their resources. However, in some cases, fighting did take place in these regions. In East Africa, for example, German General Paul von Lettow-Vorbeck led an effective guerrilla campaign against British forces. The contributions of these colonies had a significant impact, not only on the overall war effort, but also on relations between the colonial nations and their colonies. After the war, many of the promises of reform or independence made to the colonies were not fulfilled, leading to increased tensions and independence movements across the colonial world.

The First World War had a major impact on colonial territories, bringing about profound political, economic and social changes. The fighting was often carried out by colonial troops recruited by the European powers, and many territories were affected by the war. In Africa, there were clashes between French, British, Belgian and German colonial forces for control of the German territories in East Africa. This led to population displacements, economic disruption and increased exploitation of natural resources. In Asia, tensions also increased, particularly in the German colonies in China and the Pacific, which were taken over by the Japanese. Nationalist movements in India were galvanised by the war, leading to increased demands for autonomy and independence. In the Pacific, German New Guinea was taken by Australia, while New Zealand took control of German Samoa. These conflicts paved the way for new colonial arrangements after the war. The First World War therefore not only affected European nations, but also had a lasting impact on their colonies and shaped the political and social development of these regions.

The First World War profoundly disrupted the global economy. The entire global trading system was disrupted, trade between countries was reduced and the supply of essential resources was disrupted. Countries at war had to reorient their economies to support the war effort. This meant a massive increase in military production, but also a reduction in the production of consumer goods, leading to shortages and inflation. Neutral countries were also affected, as their traditional trade routes were disrupted and they had to look for new trading partners. The war also exacerbated economic and social inequalities, both between and within countries. The rich became richer as a result of the war, while the poor became poorer, leading to social and political tensions. Ultimately, the First World War undermined the existing world economic order and paved the way for subsequent economic and political crises, notably the Great Depression of the 1930s. The war dramatically demonstrated the extent to which the world's economies were interconnected and dependent on each other, and underlined the need for international cooperation and coordination to maintain global economic stability.[[fichier:Le-Monde-et-le-1er-conflit-mondial-1914-18GF.gif|center|thumb|400px|The world and the first world conflict - [http://www.atlas-historique.net/1914-1945/cartes/Monde1914-18.html atlas-historique.net]]]

The First World War was a total conflict, marked by the mobilisation of all national resources - human, economic and technological - to wage war. It was not only the armies that were involved in the conflict: civilians were also greatly affected by the war, through the bombardments, the deprivations caused by the blockade and the mass conscription of the male population.

In military terms, the war was marked by technological innovation, with the introduction of new weapons such as tanks, aircraft, submarines and poison gas. However, military strategy has often been marked by an outdated vision of war, with massive offensives costing human lives, and little room for manoeuvre or exploitation of new technologies.

Economic warfare was also a crucial factor in the conflict. The naval blockade imposed by the Royal Navy contributed in particular to weakening the German economy and causing food shortages in Germany. For their part, the Allies benefited from the economic support of the United States, which lent large amounts of money and provided resources and war material.

Finally, the war was accompanied by intense ideological propaganda. Each side sought to mobilise the nationalist sentiments of its population, dehumanise the enemy and justify the sacrifices necessary for victory. Concepts such as the "war for civilisation" or the "war for democracy" were widely used to give meaning to the war and to mobilise the population. However, these ideologies also helped to exacerbate national tensions and prepare the ground for subsequent conflicts.

=== The Colonies of the European Powers ===
The First World War also had major consequences in the colonies of the European powers. The German colonies, particularly in Africa, were the scene of fighting between the forces of the various colonial empires. British and French troops conquered the German colonies and seized their wealth, including plantations, mines and natural resources. The colonies were also called upon to contribute to the war effort, with colonial troops sent to fight on the European fronts. Several hundred thousand African, Asian and American soldiers were mobilised, often in very difficult conditions. The colonies also provided essential resources and raw materials for the war effort, such as rubber, palm oil and cotton. This led to increased exploitation of the colonies and worsening working conditions for the local populations.

=== The role of the United States ===
America's entry into the First World War sparked a national debate. On the one hand, the interventionists, who included politicians, intellectuals and journalists, argued that the United States had a moral responsibility to defend democratic values and support its allies in Europe, principally the United Kingdom and France. They were convinced that America could not remain aloof from the conflict that was redefining the global political landscape. Isolationists, on the other hand, advocated non-engagement. Many came from rural, remote areas of the Midwest and West, and were primarily concerned with domestic issues. They feared that involvement in the European conflict would damage the American economy and lead to higher taxes and possible conscription. They argued that the US should concentrate on solving its own problems and avoid getting involved in foreign conflicts. Ultimately, several factors led to the decision to enter the war in 1917, including Germany's indefinite submarine warfare which resulted in the deaths of American citizens, and the Zimmerman telegram which revealed a German proposal for Mexico to enter the war against the United States.

Several events precipitated the United States' entry into the First World War in 1917, despite intense public debate. Firstly, the attack on the Lusitania, a British liner, by a German submarine in 1915 provoked strong indignation in the United States. The incident, which resulted in the deaths of 128 Americans, was widely condemned and helped to strengthen anti-German sentiment in the United States. The discovery of the Zimmermann telegram in 1917 also played a key role. This telegram, sent by the German foreign minister to his ambassador in Mexico, proposed a military alliance between Germany and Mexico, should the United States enter the war. This revelation aroused indignation among the American population and increased pressure for the United States to enter the war. Finally, the United States' entry into the war was seen by some as an opportunity to strengthen the country's international position and promote democratic values throughout the world. This decision marked the beginning of an era in which the United States would become increasingly involved in world affairs.[[File:Zimmermann-telegramm-offen.jpg|thumb|right|alt=Zimmermann-telegramm-offen.jpg]]

The sinking of the Lusitania had a profound impact on American public opinion and helped to change American attitudes to the war. The tragedy occurred in the context of total German submarine warfare, which sought to weaken the Allies by cutting off their supply lines. The Germans had warned that all ships sailing to Britain would be considered targets, but the sinking of the Lusitania, with its heavy loss of civilian life, was seen as an inexcusable act of aggression. The event was widely reported in the American media, which presented the sinking as an act of German barbarism. It caused a public outcry and fuelled anti-German sentiment in the United States. Although the US did not enter the war immediately after the sinking of the Lusitania, the incident was a turning point that helped pave the way for the US entry into the war two years later.

The torpedoing of the Lusitania sparked outrage in the United States and put President Wilson in a difficult position. Although he had been re-elected in 1916 on the slogan "He kept us out of war", the situation was rapidly changing. After the sinking of the Lusitania, President Wilson sent several notes to Germany, demanding reparations and an end to unrestricted submarine warfare. However, US patience ran out after Germany resumed its unrestricted attacks on ships in 1917. The event helped sway public opinion in favour of intervention, and when Germany tried to incite Mexico to go to war against the US (as revealed in the Zimmermann Telegram), it was the last straw. In April 1917, President Wilson asked Congress to declare war on Germany, marking the United States' entry into the First World War.

Germany's resumption of unrestricted submarine warfare in 1917 marked a turning point in the United States' involvement in the First World War. This German policy angered the United States, which had maintained a position of neutrality since the start of the war in 1914. Unrestricted submarine warfare threatened vital Allied supplies, and by sinking neutral ships, Germany pushed the United States out of its neutrality. Germany hoped that this strategy would lead to victory before the United States could mobilise its army and navy for active combat. However, this strategy backfired. The United States made a significant contribution to the Allied war effort, both militarily and economically. Its human and material resources helped tip the balance in favour of the Allies on the Western Front, while its financial support helped maintain the Allies' fighting capacity. Ultimately, America's entry into the war played a key role in Germany's defeat and the end of the First World War in November 1918.

The Zimmerman telegram is a striking example of how espionage and cryptography played an important role during the First World War. It also helped galvanise American public support for going to war against Germany. The telegram was intercepted by British intelligence thanks to their decryption efforts. The British realised the importance of this information and realised that it could be used to influence American public opinion in favour of going to war. However, they had to be careful about how they revealed the information to the Americans, as they did not want the Germans to know that they were able to decode their encrypted messages. Once the United States had been informed, President Woodrow Wilson took the decision to make the telegram public, despite the potential risks to British intelligence capabilities. The revelation of the telegram caused an uproar in the United States and added to the public and political pressure for the country to go to war. Ultimately, the Zimmerman telegram was one of the factors that led to the United States' entry into the First World War in April 1917.

=== Japan's involvement ===
When the First World War broke out in 1914, Japan, which had formed an alliance with the United Kingdom in 1902, declared war on Germany. This gave Japan an excuse to extend its influence in Asia and the Pacific, particularly in areas that had been under German control before the war. Japan quickly occupied German island possessions in the Pacific, including the Carolines, Marshall Islands and Marianas. In mainland Asia, Japan seized control of the German concession at Qingdao, China. In addition, Japan took the opportunity to increase its influence over China. In January 1915, it presented China with the "Twenty-One Demands", which sought to establish quasi-colonial Japanese rule over China. Although China rejected some of the more extreme demands, it had to accept enough of them to significantly increase Japan's political and economic influence in China. After the war, despite some objections, Japan was able to retain most of its territorial gains at the Versailles peace conference in 1919, although this would be a source of tension with the United States and other nations in the years to come.

As well as expanding into Asia and the Pacific, Japan also played a significant role in supporting the Allied maritime efforts during the First World War. Japan, under its alliance with the United Kingdom, sent a fleet of destroyers to help protect and patrol the Pacific and Indian Oceans against German shipping. Japanese naval forces escorted Allied troop convoys, protected vital commercial shipping lanes, and actively sought out German surface raiders and submarines that threatened Allied shipping. These actions made a significant contribution to the Allied war effort in East and South-East Asian waters. Japan saw its participation in the First World War as an opportunity to improve its international position and its status as a great power. However, despite its contributions, Japan was frustrated by the treatment it received in the post-war peace settlement, fuelling nationalist and militarist sentiments that had significant repercussions in the decades that followed.

Japan's participation in the First World War played a significant role in establishing the country as a world power. By taking advantage of the opportunity to extend its influence in Asia and the Pacific, Japan succeeded in strengthening its power and influence on the international stage. The victory of Japan and the Allies in the First World War also enabled Japan to acquire several former German colonies in the Pacific, under the Treaty of Versailles. In addition, Japan was able to increase its economic and political influence in China, taking advantage of the chaos caused by the war and the revolutions underway in the country. However, despite these gains, Japan was dissatisfied with its treatment in the post-First World War world order, feeling that it had not received the recognition and respect it deserved as a world power. This feeling of dissatisfaction fuelled nationalist and militarist sentiments in Japan, contributing to the escalation of tensions in the following decades leading up to the Second World War.

=== The commitment of the Ottoman Empire ===
The Ottoman Empire played a decisive role in the First World War. It sided with the Central Powers (Germany and Austria-Hungary), provoking conflicts on several fronts, including Mesopotamia, Palestine and the Caucasus. In Mesopotamia, the Ottomans faced a British offensive aimed at securing the region's oil fields and protecting important communication routes to India. Despite fierce resistance, the Ottoman forces were finally defeated by the British in the Battle of Baghdad in 1917. In Palestine, the Ottoman Empire fought against British and French forces. The fighting was particularly intense in this region because of its strategic value, with Jerusalem as its main target. The Allied forces, led by British General Edmund Allenby, finally achieved a significant victory with the capture of Jerusalem in December 1917. In the Caucasus, the Ottomans fought against the Russians in a series of conflicts known as the Caucasus Campaign. The fighting in this region was motivated by Russia's desire to control the strategic Bosphorus and Dardanelles straits, and the Ottoman Empire's desire to suppress Armenian nationalist movements. The Ottoman Empire's involvement in the First World War had significant consequences, ultimately leading to the dissolution of the Empire at the end of the war and the establishment of the Republic of Turkey.

Control of the Dardanelles was of major strategic importance during the First World War. The Dardanelles is a narrow strait linking the Aegean Sea to the Sea of Marmara, and by extension, via the Bosphorus Strait, the Black Sea. Access to the Black Sea was essential for Russia, an ally of the Triple Entente (France, the United Kingdom and Russia), as it was one of its main export routes for grain and import route for munitions of war. In 1915, the Allies launched the Dardanelles campaign, or Gallipoli campaign, with the aim of taking control of the straits, opening up a supply route to Russia and forcing the Ottoman Empire out of the war. However, the offensive failed in the face of tenacious and well-organised Ottoman resistance. The battle was a disaster for the Allies, with heavy losses and no significant advances. At the same time, the policies of the Young Turks, the ruling party of the Ottoman Empire, led to the Armenian genocide of 1915-1917. More than a million Armenians were systematically killed or displaced in what is generally regarded as the first genocide of the 20th century. This policy also targeted other Christian minorities in the Ottoman Empire, notably the Assyrians and Pontic Greeks.

At the end of the First World War, the Ottoman Empire, which had fought alongside the Central Powers (Germany, Austria-Hungary and Bulgaria), was defeated. The Empire was occupied by Allied forces, mainly Britain and France, with specific areas under Italian and Greek control. This marked the beginning of the end of the Ottoman Empire, which had existed for around 600 years. The defeat and occupation led to many political and social changes, the most significant of which was the emergence of modern Turkey under the leadership of Mustafa Kemal Atatürk. The Treaty of Sèvres, signed in 1920, provided for the partition of the Ottoman Empire and the establishment of several nation states. However, many of the treaty's provisions were hotly contested in Turkey and led to the Turkish War of Independence led by Mustafa Kemal Atatürk and his supporters. This war eventually led to the abolition of the Sultanate and the founding of the Republic of Turkey in 1923. The Turkish War of Independence also led to the abrogation of the Treaty of Sèvres and its replacement by the Treaty of Lausanne in 1923, which established Turkey's modern borders and confirmed its independence.

=== South America in Conflict ===
Although South America was geographically distant from the main theatre of war in Europe, it was involved in the First World War in a variety of ways. Most South American countries remained neutral for most of the war, but supported the Allied war effort by providing raw materials, food and other resources.

Most South American countries, with the exception of Brazil, officially maintained their neutrality during the First World War. However, this did not prevent several of them from de facto supporting the Allies by providing raw materials, food and other resources. Brazil, in particular, declared war on Germany in 1917 after Brazilian merchant ships were torpedoed by German submarines. Brazil was the only South American country to send troops to Europe, although its military involvement was relatively limited. In addition to its military contribution, Brazil also played a key role in supplying vital resources, including rubber, coffee and meat, to the Allies. Argentina, Chile, Uruguay and Peru, although officially neutral, also supported the Allies by providing resources and allowing Allied ships to use their ports. On the other hand, countries such as Paraguay and Ecuador maintained strict neutrality throughout the war.

For the countries of South America, the First World War represented an opportunity to assert their independence and influence on the international stage. By supplying raw materials and other resources to the Allies, these countries were able to strengthen their economic and political ties with the great European powers. This enabled these countries to improve their economies, gain international recognition and establish themselves as important players in world affairs. Brazil, for example, became a founding member of the League of Nations (the predecessor of the UN) after the war, marking its rise as a regional power. As a result, participation in the war, albeit indirectly, gave these South American countries greater prestige and influence, and laid the foundations for their role in world affairs over the next century.

The participation of Brazil and certain other South American countries in the First World War enabled them to play an active role in the reconfiguration of the world order that followed. The Paris Peace Conference in 1919, which led to the signing of the Treaty of Versailles, was a crucial moment in this redefinition. Although the vast majority of decisions were taken by the major powers, the presence of these countries enabled them to take part in the discussions and present their perspectives. Their admission to the League of Nations was another important step. As members of this organisation, they had the opportunity to express their opinions on international issues and contribute to efforts to maintain world peace. In the end, although their influence was limited compared to that of the Great Powers, their involvement in the war and their participation in these organisations helped to strengthen their status and role on the international stage.

=== La Mobilisation des Empires Coloniaux ===
L'effort de guerre de la Première Guerre mondiale a nécessité une mobilisation totale des ressources de chaque empire participant, ce qui incluait non seulement la mobilisation de leurs ressources matérielles, mais aussi de leur population, y compris celles des colonies. Les empires coloniaux, notamment britannique et français, ont mobilisé leurs colonies de façon exhaustive. Des centaines de milliers de soldats coloniaux ont été recrutés pour combattre sur les fronts européens, notamment en provenance de l'Inde, de l'Afrique de l'Ouest et du Maghreb pour le compte de la Grande-Bretagne et de la France respectivement. Ces soldats ont joué un rôle crucial dans l'effort de guerre, combattant et mourant dans les tranchées aux côtés de leurs compatriotes européens. En outre, les colonies ont également fourni une main-d'œuvre précieuse en arrière du front, travaillant dans les usines d'armement, les chantiers navals, les mines et les champs agricoles pour soutenir l'économie de guerre. Cela était particulièrement vrai pour les colonies britanniques de dominion, comme le Canada, l'Australie et la Nouvelle-Zélande, qui ont non seulement envoyé des troupes, mais ont également soutenu l'effort de guerre grâce à leur production industrielle et agricole. Les empires coloniaux ont joué un rôle crucial dans la Première Guerre mondiale, contribuant de manière significative à l'effort de guerre global et jouant un rôle essentiel dans l'issue du conflit.

Les colonies ont été utilisées de manière intensive pour leur production de matières premières, qui étaient essentielles à l'effort de guerre. Les minéraux et les métaux précieux, tels que le fer, le cuivre et l'or, ont été extraits en grande quantité dans les colonies africaines, asiatiques et océaniques pour être utilisés dans la fabrication d'armes et de munitions. De même, le caoutchouc et l'huile de palme, produits principalement dans les colonies d'Asie du Sud-Est et d'Afrique, étaient indispensables à l'industrie de la guerre, utilisés respectivement dans la production de pneus et de lubrifiants. Les colonies ont également contribué à l'effort de guerre en augmentant leur production industrielle. Des usines ont été créées ou converties pour la production de biens militaires, tandis que les travailleurs coloniaux ont été recrutés en grand nombre pour travailler dans ces industries. Cette mobilisation industrielle a non seulement soutenu l'effort de guerre, mais a également entraîné des changements sociaux et économiques durables dans les colonies, en favorisant l'urbanisation et l'industrialisation. En outre, les colonies ont également été utilisées comme bases logistiques et militaires, en particulier celles situées sur les voies de navigation et de communication importantes. Les ports coloniaux ont été utilisés pour le ravitaillement des navires de guerre, tandis que les bases aériennes et les installations de communication ont été construites pour soutenir les opérations militaires. La contribution des colonies à l'effort de guerre a été multiforme et essentielle à l'issue du conflit.

Bien que les colonies aient joué un rôle crucial dans le soutien à l'effort de guerre des empires coloniaux, les conséquences pour les populations coloniales ont souvent été dévastatrices. Les conditions de travail dans les mines et les usines étaient souvent dures et dangereuses, et de nombreux travailleurs coloniaux ont été forcés de travailler contre leur volonté, dans ce qui peut être considéré comme du travail forcé. De plus, l'effort de guerre a entraîné des pénuries alimentaires et d'autres biens essentiels dans de nombreuses colonies, ce qui a eu un impact significatif sur la vie quotidienne des populations coloniales. Les restrictions imposées à la liberté de mouvement et les mesures de contrôle sévères ont également été sources de ressentiment et d'insatisfaction. En outre, la mobilisation des troupes coloniales et leur participation à la guerre ont contribué à susciter des aspirations à l'indépendance et à la libération nationale. Les soldats coloniaux qui avaient combattu aux côtés des troupes européennes ont souvent été exposés à des idées de liberté et d'égalité, et sont rentrés dans leurs colonies avec une conscience accrue de l'injustice de la domination coloniale. Ces idées ont été l'un des catalyseurs des mouvements de décolonisation qui ont émergé après la fin de la guerre. De cette manière, bien que les empires coloniaux aient cherché à exploiter leurs colonies pour soutenir l'effort de guerre, ils ont également semé les graines de leur propre déclin.

La Première Guerre mondiale a été un tournant majeur dans l'histoire mondiale, avec des répercussions qui ont bien au-delà des champs de bataille en Europe. La guerre a conduit à la mobilisation de populations et de ressources à l'échelle mondiale, y compris dans les empires coloniaux. Cela a eu un impact profond sur les sociétés coloniales, souvent à des coûts humains et économiques élevés. Pour les pays neutres, la guerre a perturbé le commerce mondial et a créé des pénuries de matières premières, ce qui a eu des effets économiques significatifs. Ces pays ont dû naviguer dans un monde en guerre, en équilibrant les besoins de leurs propres économies avec la pression pour prendre parti dans le conflit. Sur le plan politique, la guerre a transformé la carte de l'Europe et du monde. De nouveaux États ont émergé des empires qui se sont effondrés à la fin de la guerre, notamment l'Empire ottoman, l'Empire austro-hongrois et l'Empire russe. Des pays comme la Tchécoslovaquie, la Yougoslavie et la Pologne sont apparus, redessinant les frontières de l'Europe. Finalement, les idéaux de démocratie et d'autodétermination promus pendant la guerre ont alimenté les aspirations nationalistes et anti-coloniales à travers le monde. La guerre a également conduit à la création de la Société des Nations, une tentative (bien que finalement infructueuse) d'établir un système international pour prévenir de futurs conflits. La Première Guerre mondiale a été un conflit véritablement mondial, avec des répercussions qui ont remodelé le monde dans lequel nous vivons aujourd'hui.

= Réflexions Finales : L’Europe au Centre du Monde, de la Fin du XIXe Siècle à 1918 =
Cette période, souvent appelée "l'âge des empires", a été marquée par l'expansion européenne et l'impérialisme à travers le monde. Les empires européens, notamment le Royaume-Uni, la France, l'Allemagne, l'Espagne, le Portugal, les Pays-Bas, l'Italie, et la Belgique, ont étendu leur influence à des territoires en Asie, en Afrique, aux Amériques et dans le Pacifique. Ils ont cherché à contrôler ces régions pour leurs ressources naturelles, leurs marchés et leur main-d'œuvre, et ont souvent imposé leur culture, leur langue et leur système politique aux populations locales. En Europe même, le système politique était dominé par un réseau complexe d'alliances et de rivalités entre les grandes puissances, ce qui a finalement conduit à l'éclatement de la Première Guerre mondiale. Sur le plan économique, l'Europe était le centre du commerce mondial, avec des empires industriels émergents comme l'Allemagne et des empires commerciaux établis comme le Royaume-Uni. Culturellement, l'Europe a également exercé une influence significative. La langue, la littérature, la philosophie, la musique, et l'art européens ont eu un impact mondial. Des idéaux comme le libéralisme, le socialisme, le nationalisme, et le darwinisme ont été largement diffusés et débattus à la fois en Europe et au-delà. Cette période a également été marquée par des résistances et des contestations. Les mouvements anti-coloniaux ont commencé à émerger dans de nombreuses colonies, et les tensions sociales et politiques en Europe ont mené à des bouleversements majeurs, y compris la Révolution russe et la Première Guerre mondiale. Ces événements ont finalement contribué à la fin de l'ère de la domination européenne et ont ouvert la voie à l'émergence de nouvelles puissances mondiales au cours du XXe siècle. 

La Première Guerre mondiale a profondément modifié le paysage politique, économique et social du monde. Sur le plan politique, la guerre a conduit à la chute de plusieurs empires, notamment les empires russe, allemand, ottoman et austro-hongrois. En même temps, elle a donné naissance à de nombreux nouveaux États-nations en Europe de l'Est et au Moyen-Orient. Elle a également marqué l'émergence des États-Unis comme superpuissance mondiale, ce qui a modifié l'équilibre des pouvoirs internationaux. Sur le plan économique, la guerre a causé d'énormes pertes matérielles et a perturbé le commerce mondial. Les coûts financiers de la guerre ont conduit à une inflation et à une dette importantes dans de nombreux pays, qui ont semé les graines de la Grande Dépression des années 1930. Sur le plan social, la guerre a causé la mort de millions de personnes et a laissé de nombreuses autres blessées ou traumatisées. Elle a également changé le rôle des femmes dans la société, beaucoup d'entre elles ayant dû prendre en charge des emplois traditionnellement masculins pendant que les hommes étaient à la guerre. La guerre a également stimulé les mouvements de libération coloniale et les mouvements nationalistes à travers le monde. La promesse des Alliés d'une "paix basée sur le droit des peuples à disposer d'eux-mêmes" a éveillé des aspirations à l'indépendance dans de nombreuses colonies. Enfin, l'insatisfaction face aux termes du Traité de Versailles, qui mettait fin à la guerre, a contribué à l'émergence de mouvements radicaux et totalitaires, notamment le fascisme en Italie et le nazisme en Allemagne, ce qui a finalement conduit à la Seconde Guerre mondiale.

À la fin de la Première Guerre mondiale, la Société des Nations a été créée dans le but de maintenir la paix mondiale et de prévenir de futurs conflits. Cela a été l'un des principaux points du programme des "Quatorze Points" du président américain Woodrow Wilson, qui a été présenté comme un plan pour la paix après la guerre. La Société des Nations a été le premier organisme international de ce type, et elle a servi de forum pour la résolution pacifique des conflits. Toutefois, elle a rencontré de nombreux défis et limitations, notamment le fait que les États-Unis n'ont jamais rejoint l'organisation malgré l'implication de Wilson dans sa création. Malgré ses ambitions, la Société des Nations a été incapable d'empêcher les agressions des puissances fascistes dans les années 1930, et elle a finalement été dissoute pendant la Seconde Guerre mondiale. Quant à la montée du nazisme en Allemagne, elle est directement liée aux conséquences de la Première Guerre mondiale. Les conditions de la paix définies par le Traité de Versailles étaient sévères pour l'Allemagne, qui a été tenue responsable du déclenchement de la guerre et a été contrainte de payer des réparations écrasantes. Ces conditions, associées à la crise économique qui a suivi, ont contribué à créer un sentiment de ressentiment et de désespoir en Allemagne, créant un terreau fertile pour l'extrémisme et le nationalisme qui ont conduit à la montée du parti nazi.

La Première Guerre mondiale, en particulier, a marqué la fin de l'âge d'or de l'impérialisme européen et a remodelé la carte politique et économique du monde. De nombreux empires, comme l'Empire russe, l'Empire allemand, l'Empire austro-hongrois et l'Empire ottoman, se sont effondrés à la suite de la guerre. En même temps, de nouveaux pays ont été créés et de nouvelles forces, comme les États-Unis et le Japon, ont commencé à affirmer leur puissance sur la scène mondiale. La guerre a également laissé un lourd héritage de traumatismes, de pertes et de désillusionnement, qui a affecté des générations de personnes à travers le monde. De plus, les conditions sévères imposées à l'Allemagne par le traité de Versailles ont contribué à la montée de l'extrémisme et à l'éclatement de la Seconde Guerre mondiale quelques décennies plus tard. En fin de compte, l'impact de cette période sur l'histoire du monde a été monumental, et ses conséquences se font encore sentir à ce jour.

La Première Guerre mondiale a marqué un tournant majeur dans l'histoire mondiale, déclenchant une série de transformations qui ont réorganisé la carte politique du monde. Les empires européens, qui avaient dominé le monde pendant des siècles, ont été profondément affaiblis par la guerre. Les empires allemand, austro-hongrois, russe et ottoman se sont effondrés, et de nouveaux États ont été créés dans leurs anciens territoires. Les empires britannique et français ont survécu à la guerre, mais ont été affaiblis et ont dû faire face à de nombreux défis, notamment l'agitation dans leurs colonies et les crises économiques à domicile. Dans le même temps, la guerre a marqué l'émergence de nouvelles puissances sur la scène mondiale. Les États-Unis, qui étaient restés largement isolés des affaires européennes avant la guerre, sont devenus une superpuissance économique et militaire. L'économie américaine a été boostée par la demande de produits industriels et agricoles pendant la guerre, tandis que la victoire a renforcé le prestige et l'influence internationale des États-Unis. De même, la Russie, qui a traversé une révolution en 1917 et est devenue l'Union soviétique, a commencé à jouer un rôle majeur dans la politique mondiale. Malgré l'isolation initiale de l'Union soviétique, le pays allait devenir une superpuissance mondiale au cours du XXe siècle. En outre, la guerre a également accéléré l'ascension du Japon comme une puissance majeure en Asie et dans le Pacifique. En profitant de la guerre pour étendre son influence, le Japon a établi les bases de son expansion impérialiste dans les décennies suivantes.

Les conséquences économiques de la Première Guerre mondiale ont été majeures et ont conduit à un réalignement significatif de la puissance économique mondiale. Avant la guerre, les pays européens, en particulier le Royaume-Uni et l'Allemagne, étaient les leaders mondiaux de l'industrie et du commerce. Cependant, les dommages immenses causés par la guerre, ainsi que le fardeau de la dette de guerre, ont considérablement affaibli les économies européennes. D'autre part, les États-Unis, qui étaient relativement isolés du conflit direct jusqu'en 1917, ont pu prospérer en fournissant des biens et des prêts aux nations belligérantes. Après la guerre, avec une industrie puissante et une économie florissante, les États-Unis sont devenus la principale puissance économique mondiale. Par ailleurs, la Première Guerre mondiale a planté les graines de futurs conflits, en particulier la Seconde Guerre mondiale. Le traité de Versailles, qui a mis fin à la Première Guerre mondiale, a imposé de lourdes réparations à l'Allemagne et a redessiné la carte de l'Europe de manière controversée. Ces conditions ont semé le mécontentement et le ressentiment en Allemagne et ailleurs, créant un terreau fertile pour les mouvements extrémistes comme le nazisme et conduisant finalement à la Seconde Guerre mondiale. Ainsi, la Première Guerre mondiale a non seulement redéfini l'ordre politique mondial, mais a également entraîné un réalignement économique majeur et a jeté les bases de conflits futurs.

La Première Guerre mondiale marque une transition clé dans l'histoire mondiale. L'Europe, qui avait longtemps dominé la scène mondiale politiquement, économiquement et culturellement, a vu son influence réduite à la suite de la guerre. Les pertes humaines et matérielles énormes, le fardeau économique de la reconstruction et de la dette de guerre, et les tensions politiques internes ont affaibli les puissances européennes. Pendant ce temps, de nouvelles puissances ont commencé à émerger sur la scène mondiale. Les États-Unis, en particulier, ont vu leur influence augmenter après la Première Guerre mondiale. En raison de leur intervention tardive dans la guerre, ils ont souffert de pertes beaucoup moins importantes que les puissances européennes, et leur économie est devenue l'une des plus fortes du monde. De plus, l'Union soviétique, née de la Révolution russe de 1917, a émergé comme une nouvelle superpuissance avec une idéologie qui défiait l'ordre mondial existant. La fin de la guerre a également vu le démantèlement des grands empires en Europe, tels que l'Empire russe, l'Empire austro-hongrois et l'Empire ottoman, et la création de nouveaux États nationaux en Europe de l'Est et au Moyen-Orient. Ces changements ont redéfini l'équilibre des pouvoirs mondiaux et ont conduit à de nouvelles tensions et conflits, jetant les bases de la Seconde Guerre mondiale. La Première Guerre mondiale est donc un tournant majeur dans l'histoire mondiale, qui a bouleversé l'ordre mondial existant et a façonné le monde tel que nous le connaissons aujourd'hui.

= Annexes =
*Foreign Affairs,. (2015). Europe without the League. Retrieved 19 September 2015, from https://www.foreignaffairs.com/articles/western-europe/1939-10-01/europe-without-league
*Foreign Affairs,. (2015). How Europe Conquered the World. Retrieved 8 October 2015, from https://www.foreignaffairs.com/articles/europe/2015-10-07/how-europe-conquered-world
*Quand l'Europe dominait le monde et ses richesses. Abo.monde-diplomatique.fr,. (2015). Retrieved 19 September 2015, from http://abo.monde-diplomatique.fr/media/pdf/atlas_histoire/10-11.pdf

= References =
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[[Category:Ludovic Tournès]]
[[Category:histoire]]
[[Category:relations internationales]]