II Field Force, Vietnam was a United States Army Corps-level command during the Vietnam War.Activated on 15 March 1966, it became the largest corps command in Vietnam and one of the largest in Army history. II Field Force was assigned the lineage of the XXII Corps, a World War II corps in the European Theater of Operations. II Field Force was a component of U.S. Military Assistance Command Vietnam (MACV) and had its headquarters in Long Binh.