What role did the United States play in World War I?

The United States played a significant role in World War I by joining the Allies in 1917 and providing military support, which was crucial to the war's outcome. Initially, the U.S. maintained a stance of neutrality, focusing on its own internal matters and avoiding involvement in the conflict. However, various factors, including unrestricted submarine warfare by Germany and the interception of the Zimmermann Telegram, shifted public opinion and government policy toward joining the war.

By entering the conflict, the U.S. contributed not only troops but also resources and supplies, which bolstered the Allied forces. The American Expeditionary Forces engaged in major battles, such as those at Cantigny and the Meuse-Argonne, and helped to turn the tide against the Central Powers. The involvement of fresh American troops and resources provided a much-needed boost to the struggling Allied forces, ultimately leading to a swift conclusion of hostilities in November 1918.