John J. Pershing was the significant historical figure known for leading the American forces in World War I. As a general, he played a crucial role in organizing the American Expeditionary Forces and coordinating with Allied leaders to strategize military efforts. His emphasis on rigorous training and maintaining a separate American command helped bolster the effectiveness of U.S. forces in the war. Pershing's leadership significantly contributed to the eventual Allied victory in 1918 and shaped post-war military policy.