A series of events unfolded that drew the U.S. into World War I, including Germany's sinking of merchant ships like the Lusitania which killed American citizens, the Zimmerman Telegram proposing a German alliance with Mexico against the U.S., and Germany's declaration of unrestricted submarine warfare which led them to sink numerous U.S. ships and turn public opinion against neutrality. Faced with growing support to enter the war and protect American interests, President Wilson asked Congress to declare war on Germany in April 1917.