Causes Of World War One Nick Karalius By Nick Karalius Period: Jul 23, 1914 to Nov 23, 1918 World War I Events that caused America to join the war. Aug 3, 1914 British Naval Blockade May 7, 1915 Lusitania sinking Mar 28, 1916 Sussex sinking Aug 13, 1916 Arrabic sinking Nov 30, 1916 He kept us out of war Jan 1, 1917 Pease without victory Jan 22, 1917 Zimmermann note Jan 31, 1917 Resumption of unrestricted submarine warfare Mar 18, 1917 Overthrow of Nicholas II Apr 2, 1917 Declaration of war against the Central Powers Apr 12, 1917 Presidant Wilson's war message