When did World War I start?
World War I started on July 28, 1914, when Austria-Hungary declared war on Serbia. Within days, alliances drew in Germany, Russia, France and Britain.
The spark came on June 28, 1914, when Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, was assassinated in Sarajevo by Gavrilo Princip, a Bosnian Serb. Austria-Hungary blamed Serbia and, backed by Germany, declared war a month later.
Russia mobilized to support Serbia, Germany declared war on Russia on August 1 and on France on August 3, and Britain entered the war on August 4 after Germany invaded neutral Belgium. Soon the Ottoman Empire, Japan and later Italy and the United States joined in.
How it ended
The war ended with an armistice at 11 a.m. on November 11, 1918, still remembered as Armistice Day. About 15 to 20 million people died. The Treaty of Versailles in 1919 set the peace terms, and four empires, the German, Austro-Hungarian, Russian and Ottoman, collapsed.
Did You Know?
At the time, people called it the Great War. The name World War I came into wide use only after a second world war began in 1939.