World War I had a huge impact on the culture and technology of war, initiating social changes, reshaping national boundaries across the globe, and setting the United States on the path to becoming a world superpower. It was also the beginning of the Army’s reliance on a large federal Reserve force that would eventually form the U.S. Army Reserve of today – capable, combat-ready, lethal units, trained and equipped to meet the operational needs of the Army and the Joint war-fighting environment to win the Nation’s wars. Four million American men and women served in uniform during World War I, and more were killed during America’s short 18-month involvement in World War I, than during the entire Vietnam War and Korean Conflict combined.