WW1 By _dshepherd7 Period: Apr 4, 1914 to Jun 28, 1919 World War 1 Austria-Hungary's Archduke Francis Ferdinand assassinated while visiting Sarajevo, Bosnia Jun 28, 1914 Austria-Hungary's Archduke Francis Ferdinand assassinated while visiting Sarajevo, Bosnia Austria-Hungary's Archduke Francis Ferdinand assassinated while visiting Sarajevo, Bosnia Aug 1, 1914 Germany declares war on Russia May 7, 1915 British ocean liner Lusitina sunk by German U-boat Apr 4, 1916 Trench Warfare Apr 4, 1917 U.S. joins war due to continued unrestriced sub warfare