S. J. Res. 1, Declaration of War on Germany, April 2, 1917
On April 2, 1917, Senator Thomas S. Martin of Virginia introduced a joint resolution to declare war on the Imperial German Government, stating that war had been thrust upon the United States. It authorized the president to take steps to bring the conflict to a successful termination. After two days of debate, the Senate approved the joint resolution by a vote of 82–6.
Records of the U.S. Senate, National Archives and Records Administration
World War I: Declaring War on Germany
On April 2, 1917, President Woodrow Wilson asked a joint session of Congress to declare war on Germany. The president cited Germany’s repeated submarine attacks on passenger and merchant ships and its attempt to entice Mexico into an alliance against the United States as his reasons for Congress to declare war. On April 4, 1917, the Senate voted in support of the measure, and the House concurred two days later. The United States later declared war on German ally Austria-Hungary on December 7, 1917.
We are going to war . . . to vindicate our honor and to maintain our independence as a great nation. We are going to war . . . in defense of humanity.
Senator Gilbert Hitchcock of Nebraska, Speech to the U.S. Senate, April 4, 1917