The USA joins the war

Wilson tried very hard to keep the U.S. out of the war, and this also played an important part in his re-election in 1916. He had been campaigning as the 'peace' candidate and his campaign slogan was; He kept us out of the war. But more and more Americans understood that they would have to join the war sooner or later. In January 1917 a German official named Arthur Zimmermann sent a letter to the German ambassador in Mexico where he instructed him to make an offer to the Mexican government. The offer was that if Mexico joined Germany as an ally Mexico would regain its 'lost territory in Texas, New Mexico and Arizona' after the war. Germany hoped Mexico could keep the American forces busy so they would not interfere in Europe. This letter was leaked to Americans newspapers, and furious Americans now concluded that war with Germany was necessary.

When Germany on February 1, 1917 resumed their unrestricted submarine warfare and on February 3 and March 21 sank six American merchant ships without warning. President Wilson now saw no other possibility than war with Germany. Wilson appeared before a special congress on April 2, 1917 to ask for a declaration of war against Germany, this passed by the Senate with 82-6 and the House with 373-50. It was now clear, America was going to war.