Congress debates and votes on a declaration of war against Germany. The Senate approves the declaration on April 4 by a vote of ; on April 6, the House of Representatives passes the resolution by a vote of Wilson signs the declaration on April 6. On April 6, , the United States declared war on Germany. Although President Woodrow Wilson had campaigned for reelection in emphasizing how he had kept the United States out of the war, he soon realized that the United States could not stand by and remain neutral in the Great War.
At the end of January , German U-Boats resumed unrestricted submarine warfare, attacking ships in the Atlantic Ocean. Shortly afterwards, the British released the Zimmermann telegram to the American government.
The telegram revealed a German plot to try to entice Mexico into joining against the United States. Nevertheless, Wilson remained locked in a remarkable struggle between conflicting principles in his own ideology over the decision whether to go to war.
Congress and the public were divided enough on the issue of intervention that the decision to enter the Great War fell on Wilson alone. But he feared that war would undo the progressive reforms he sought domestically and exacerbate the social divisions already present in the country.
Nevertheless, Wilson believed that German behavior stood out of bounds of the civilized world and that a German victory would have disastrous consequences for Western civilization.
