World War I began on July 28, 1914 and lasted until November 11, 1918. It involved many of the world's major powers divided into two opposing alliances: the Allies including Britain, France, and Russia, and the Central Powers including Germany and Austria-Hungary. The war was sparked by the assassination of Archduke Franz Ferdinand of Austria by Serbian nationalists, which caused Austria-Hungary to declare war on Serbia and aligned countries to join the fighting. Over 10 million soldiers and civilians lost their lives in the war before an armistice was signed and the Treaty of Versailles ended the war.