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. Area of Responsibility and Units Assigned I Field Force's area of responsibility was II Corps Tactical Zone, later renamed Military Region 2, which comprised the twelve provinces of Vietnam's Central Highlands. Among the divisions and brigades it controlled were: 1st Cavalry Division (Airmobile) 4th Infantry Division 3d Brigade, 25th Infantry Division 1st Brigade, 101st Airborne Division 173rd Airborne Brigade 41st Artillery Group 52nd Artillery Group 77th Radar Detachment 54th Signal Battalion Inactivation I Field Force was inactivated on 30 April 1971 during the withdrawal of U.S. ground combat forces from Vietnam, and its assets formed the basis for its successor, the Second Regional Assistance Command (SRAC). Commanders LTG Stanley R. Larsen March 1966 – July 1967 LTG William B. Rosson July 1967– February 1968 LTG William R. Peers March 1968 – March 1969 LTG Charles A. Corcoran March 1969 – March 1970 LTG Arthur S. Collins Jr. March 1970 – January 1971 MG Charles P. Brown January 1971 – April 1971 Notes Sources Military units and formations of the United States Army in the Vietnam War Corps of the United States Army Military units and formations established in 1966 Military units and formations disestablished in 1971