World War I

Also known as the Great War, World War I (1914-1918) was one of the deadliest conflicts in history. The war pitted two major alliances against one another: The Allies (France, Britain, Russia, Italy, and later the United States) and the Central Powers (Germany, Austria-Hungary, the Ottoman Empire, and Bulgaria). It was primarily fought in Europe, with key fronts in France and Belgium and in Eastern Europe, as well as in the Middle East, Africa, and Asia.

Unprecedented in its level of violence and numbers of dead, World War I claimed an estimated 16 million lives, including 7 million civilians. It resulted in political, social and economic upheaval and brought about the collapse of imperial dynasties in Germany, Austria-Hungary, Ottoman Turkey, and Imperial Russia and the emergence of smaller nation-states, particularly in Central and Eastern Europe.

World War I ended with the surrender of Germany in 1918. A formal peace treaty, the Treaty of Versailles, imposed heavy reparations and territorial losses on Germany, which exacerbated economic challenges and political instability in the country. These factors later influenced the rise of Adolf Hitler and National Socialism in Germany, leading to the outbreak of World War II.