The United States' participation in the First World War marked a significant turning point in the nation's role in world affairs. Prior to the war, the U.S. had pursued a policy of isolationism and avoided involvement in European conflicts. However, the U.S.'s entry into the war in 1917 signaled a shift away from isolationism and towards active engagement in global affairs. The U.S. played a significant role in bringing an end to the war, both through military contributions and diplomatic efforts. The country's military and economic resources helped to tip the balance in favor of the Allies, leading to their ultimate victory in 1918. Additionally, the U.S. played a central role in the postwar negotiations that led to the Treaty of Versailles, which formally ended the war. The U.S.'s participation in the war also marked a shift towards a more assertive foreign policy. In the aftermath of the war, the U.S. emerged as a major world power and assumed a leading role in global affairs. The country took an active role in creating and supporting the League of Nations, and President Woodrow Wilson's Fourteen Points set the stage for postwar diplomacy. Overall, the U.S.'s participation in the First World War marked a significant turning point in the nation's role in world affairs. It signaled a shift away from isolationism and towards a more active and assertive foreign policy, setting the stage for the U.S. to emerge as a major global power in the 20th century.