At the time, the United States had a policy of neutrality, meaning it did not take sides in the war between the Allied Powers and the Central Powers. However, Germany's actions violated American neutrality and led the United States to enter the war on the side of the Allies.
Immediately following America's declaration of war, the country began mobilizing its military forces and preparing for deployment to Europe. The American Expeditionary Force (AEF) was formed, and General John J. Pershing was appointed as its commander. The AEF began arriving in France in June 1917 and eventually reached a strength of over two million troops.
The American forces played a significant role in the Allied victory in World War I. They were involved in several major battles, including the Meuse-Argonne Offensive, which was the largest and bloodiest battle in American history. The AEF also provided vital support in other areas, such as logistics, aviation, and medical care.
By the time the war ended in November 1918, the American forces had suffered over 350,000 casualties, including over 53,000 deaths. The United States emerged from the war as a major world power and played a key role in shaping the post-war world.