WWI By alex cuevas Jun 28, 1914 Assassination of Archduke Franz Ferdinand by Gavrilo Princip Jul 28, 1914 WWI started because the Austrian-Hungarian war declaration in Serbia Period: Jul 28, 1914 to Nov 11, 1918 World War One Jul 30, 1914 Russia joined the war declaring war to Austria-Hungary, in defense of Serbia Aug 4, 1914 Germany joined the WWI declaring war to Russia, France and Belgium Nov 5, 1914 The Ottoman Empire (Turkey) joined the war Dec 24, 1914 Christmas Truce May 23, 1915 Italy joined the war in the side of the Entente Apr 6, 1917 United States declared war to Germany Nov 7, 1917 Russian revolution of the Soviet Union and Russia left the war Nov 11, 1918 The WWI ended in an armistice Jun 28, 1919 The Treaty of Versailles