The United States had many allies and enemies during World War I. Our enemies were called the Central Powers, while our allies were just referred to as the Allies. Many countries became involved in the war because they had treaties with other countries. There were many key events that caused other countries to become involved in the war. Our allies and enemies during the war affected our country and everything we did. There were various important figures during World War I, whether political or military leaders. Various policies and decisions were made by different countries during World War I, and they affected the outcome of the war. The events of World War I greatly affected foreign policy in the United States.