World War I: Causes, Alliances, and Major Battles

Colonialism and Nationalism

Colonialism and nationalism fueled rivalries between colonial powers for territories. In 1905, nationalist agitation led to a confrontation between France and Germany over Alsace-Lorraine. A rivalry also existed between France and Britain for control of trade routes and sea lanes.

Alliances and Arms Race

The arms race saw states invest heavily in armaments, including the construction of warships and troop training. Alliances aimed to prepare for potential confrontations. The Triple Alliance of 1882 comprised Germany, Austria-Hungary, and Italy. The Triple Entente, formed in 1907, included France, Russia, and Britain.

The Outbreak of War

The immediate cause of the war was the assassination in Sarajevo of Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, by a Bosnian nationalist. Austria-Hungary declared war on Serbia. Russia mobilized to protect Serbia. Germany declared war on Russia and France. Great Britain declared war on the Triple Alliance after German troops invaded neutral Belgium in June 1914.

The Great War (1914-1918)

The War's Initial Phase

Germany's initial offensive involved a rapid movement through Belgium and Luxembourg into France. By September 1914, German forces were within 40 km of Paris. The Battle of the Marne in September saw French and British forces halt the German advance.

Trench Warfare

The Western Front became characterized by trench warfare and static lines. Bloody battles like the Somme and Verdun resulted in thousands of deaths. New allies joined the conflict: Italy joined the Triple Entente in 1915, while Bulgaria and the Ottoman Empire supported the Central Powers (formerly the Triple Alliance). The Battle of Verdun in 1916 was a German offensive aimed at breaking the French front, but French and Allied forces resisted, suffering 1,800,000 casualties.

The Crisis of 1917 and the War's End

The Russian Revolution led to Russia's withdrawal from the war and a peace treaty with Germany (Treaty of Brest-Litovsk). The United States entered the war, declaring war on Germany following the sinking of the Lusitania. The war concluded in 1918 with Allied victories on multiple fronts. The Eastern Front saw British, French, and Italian forces defeat Austrian and allied troops. The Austro-Hungarian and Ottoman Empires sought armistices. On the Western Front, German forces were defeated, leading to army revolts and worker demonstrations against the government. Fearing a revolutionary state, Kaiser Wilhelm II abdicated, and Germany sought an armistice in 1918.