I Field Force, Vietnam was a corps-level command of the United States Army during the Vietnam War. Activated on 15 March 1966, it was the successor to Task Force Alpha, a provisional corps command created 1 August 1965 (renamed Field Force Vietnam on 25 September) for temporary control of activities of U.S. Army ground combat units arriving in Vietnam. I Field Force was a component of U.S. Military Assistance Command Vietnam (MACV) and had its headquarters at Nha Trang.