The Begining of World War I By Keelia Jul 19, 1870 Napolean III Declared War on Prussia May 20, 1882 triple alliance Jun 18, 1887 Reinsurance Treaty Aug 18, 1892 France- Russian militatry Apr 8, 1904 Entente Cordiale Jul 8, 1908 Anglo- Russian Entente Jun 28, 1914 Archduke Franz Assassination Jul 28, 1914 Austria-Hungary declared war on Serbia Aug 9, 1914 Russia enters war Aug 6, 1917 United States Enters War Sep 1, 1939 Germany Enters War Allied to Austria-Hungary