World War I

World War I was a global conflict that began in 1914 and ended in 1918. It divided the world into two camps: the Allies (Britain, France, Russia, and later Italy and the United States) and the Central Powers (Germany, Austria-Hungary, the Ottoman Empire, and Bulgaria). The war took place in Europe, the Middle East, Africa, and at sea, and resulted in millions of military and civilian deaths.

The war resulted in the collapse of four empires—Germany, Austria-Hungary, Russia, and the Ottoman Empire—and the creation of many new states in Eastern and Central Europe. The peace treaties of 1919–1920, particularly the Treaty of Versailles, imposed heavy conditions on Germany, which contributed to tensions over the following two decades.

Causes and origins

Before 1914, the great powers of Europe had formed military alliances facing one another and competed over armaments, colonial territories, and markets. Particular tension existed in the Balkans, where emerging nationalisms and the rivalries of Austria-Hungary and Russia came into conflict. In June 1914, the assassination of Archduke Franz Ferdinand in Sarajevo triggered serious disputes and diplomatic crises; in July and August 1914, the major powers mobilized their armies and declared war one after another.

Warfare and technology

The Western Front—stretching between Belgium and France—became characterized by trench warfare, with both sides digging extensive trenches and front-line movement minimal for years. New weapons such as machine guns, artillery, poison gas, tanks, and aircraft increased casualties dramatically. The Eastern Front saw more mobile operations; fighting also occurred in Italy, the Balkans, Gallipoli, Iraq, and the Levant. At sea, German submarines attacked merchant shipping, an action that influenced the United States' entry into the war in 1917.

End of the war

In 1917, Russia experienced internal revolution and the new government withdrew from the war. That same year the United States joined the Allies, adding financial and military strength to that side. German offensives in summer 1918 failed to achieve a breakthrough, and the Central Powers began signing armistices one by one. The general ceasefire came on 11 November 1918.

Impact

The war transformed the political map of Europe and the Middle East and introduced new methods by which states controlled economies and populations during wartime. The League of Nations was established to prevent future wars. The resentment of some parties to the peace treaties and the economic difficulties that followed are regarded as factors leading to World War II.