The United States entered World War I (1914-18) in April 1917. A massive build-up of American troops occurred, swelling the military ranks from around five hundred thousand combat-ready soldiers in 1917 to around two million in 1918. Vital industries at home were geared to the war effort, building the boats, vehicles, and supplies needed for the war.

In January 1918, as American troops were being prepared for a more massive involvement, President Woodrow Wilson (1856-1924; see entry in volume 4) presented his Fourteen Points to Congress. The Fourteen Points summarize the aims of the Allied Powers—those nations united in the war against the Central Powers of Germany, Austria-Hungary, and Turkey. Later in 1918, the Fourteen Points became the list of demands the Central Powers had to meet in order to secure an armistice (cease fire) and begin serious peace negotiations.

Throughout the war, Wilson pursued various means to...