On March 24 1916 - the French ( though I have seen it referred to as English !! ) cross-channel steamer Sussex was torpedoed and fifty United States citizens on board were killed. The Sussex Pledge didn't last .... as the war raged on in 1916 - the German High Command became convinced that - not only could they break Britain using a full policy of unrestricted submarine warfare, they could do it before America was in a position to fully join the war. Consequently, on February 1st 1917 - Germany broke the Sussex Pledge and returned to sinking all 'enemy' craft. These actions contributed heavily to America's declaration of war on Germany, issued April 6th 1917.
