U.S. Entry into World War I, 1917
On April 2, 1917, President Woodrow Wilson went before a joint session of Congress to request a declaration of war against Germany. Wilson cited Germany’s violation of its pledge to suspend unrestricted submarine warfare in the North Atlantic and the Mediterranean, as well as its attempts to entice Mexico into an alliance against the United States, as his reasons for declaring war. On April 4, 1917, the U.S. Senate voted in support of the measure to declare war on Germany. The House concurred two days later. The United States later declared war on German ally Austria-Hungary on December 7, 1917. World War I Trenches in France Germany’s resumption of submarine attacks on passenger and merchant ships in 1917 became the primary motivation behind Wilson’s decision to lead the United States into World War I. Following the sinking of an unarmed French boat, the Sussex, in the English Channel in March 1916, Wilson threatened to sever diplomatic relations with Germany unless the German Gover