Wilson’s re-election in 1916 owed a great deal to the campaign
slogan, “He kept us out of war.” But the resumption of unrestricted
submarine warfare by Germany in 1917 significantly changed the
international situation. Several U.S. merchant ships were sunk in
March by German U-boats. That April Wilson called Congress
into extraordinary session to ask for a declaration of war against
Germany. Within four days both the Senate and the House voted
overwhelmingly to support the President.