World War I By bakus522 Jun 28, 1914 Archduke Ferdinand of Austria-Hungary is assassinated by a Serbian. Jul 28, 1914 Austria-Hungary declares war on Serbia Jul 30, 1914 Russia mobilizes Aug 1, 1914 Germany declares war on Russia Aug 3, 1914 Germany declares war on France Aug 4, 1914 Britain declares war on Germany Aug 6, 1914 Austria-Hungary declares war on Russia Aug 12, 1914 France and Britain declare war on Austria-Hungary Apr 6, 1917 The United States joins its allies, France, Britain, and Russia in war Nov 11, 1918 Armistice of WWI Jun 28, 1919 Treaty of Versailles is signed