When the Great War began in the summer of 1914, President Woodrow Wilson proclaimed "The United States must be neutral in fact as well as in name during these days that are to try men's souls."

While war raged overseas, the United States remained officially neutral. However, citizens raised funds for both sides, and shipped millions of tons of relief and war goods to Europe. Americans volunteered to fly, fight, and heal the wounded. Still, the majority of Americans believed this was not their war. In November 1916, Wilson won re-election under the slogan "He kept us out of war."

In January 1917, Germany resumed unrestricted submarine warfare, with the hope it would end the European stalemate. Shortly after, the U.S. learned of a telegram sent by German Foreign Secretary Arthur Zimmermann, enticing Mexico to invade the U.S. in exchange for American territory. In March, the fall of Russia's monarchy simplified the moral argument for the Allied cause: the war was now between democratic nations and autocratic empires.

In response to these events, on April 2, Wilson went before the U.S. Congress and stated: "the world must be made safe for democracy." Four days later, on April 6, 1917, the United States declared war.