World War I

1914-07-28 - 1918-11-11

World War I, or the First World War (28 July 1914 - 11 November 1918), also known as the Great War, was a global conflict between two coalitions: the Allies (or Entente) and the Central Powers. It was one of the deadliest conflicts in history, with an estimated 15 to 22 million deaths. Tensions reached a breaking point when Gavrilo Princip assassinated Archduke Franz Ferdinand on 28 June 1914, and Austria-Hungary declared war on Serbia on 28 July. The United States joined the Allies in April 1917, and the war ended with the Armistice of 11 November 1918 after Kaiser Wilhelm II abdicated. The Treaty of Versailles imposed settlements on the defeated powers, and the League of Nations was established to maintain world peace.