Military Assistance Command, Vietnam

U.S. Military Assistance Command, Vietnam (MACV) was a joint-service command of the United States Department of Defense.
MACV was created on 8 February 1962, in response to the increase in United States military assistance to South Vietnam. MACV was first implemented to assist the Military Assistance Advisory Group (MAAG) Vietnam, controlling every advisory and assistance effort in Vietnam, but was reorganized on 15 May 1964 and absorbed MAAG Vietnam to its command when combat unit deployment became too large for advisory group control. MACV was disestablished on 29 March 1973 and replaced by the Defense Attaché Office (DAO), Saigon . The DAO performed many of the same roles of MACV within the restrictions imposed by the Paris Peace Accords until the Fall of Saigon.
The first commanding general of MACV (COMUSMACV), General Paul D. Harkins, was also the commander of MAAG Vietnam, and after reorganization was succeeded by General William C. Westmoreland in June 1964, followed by General Creighton W. Abrams (July 1968) and General Frederick C. Weyand (June 1972).
Establishment and growth.
Admiral Harry D. Felt, Commander-in-Chief, Pacific, established the U.S. Military Assistance Command, Vietnam, on 8 February 1962, as a subordinate unified command under his control. Lieutenant General Paul D. Harkins, the Deputy Commander in Chief, U.S. Army, Pacific, who, as the commander-designate for the task force headquarters (HQ) in the event of operations in Southeast Asia, had participated in the planning for such operations, was appointed commander, and promoted to general. General Harkins became the senior U.S. military commander in Vietnam and, responsible for U.S. military policy, operations, and assistance there. General Harkins had the task of advising the Vietnamese government on security, organization, and employment of their military and paramilitary forces. As provided for in the organization of the task force headquarters in the contingency plans, MACV's commander was also his own Army component commander. With an initial authorized strength of 216 men (113 Army), MACV was envisaged as a temporary HQ that would be withdrawn once the Viet Cong insurgency was brought under control. In that event, the Military Assistance Advisory Group would be restored to its former position as the principal U.S. headquarters in South Vietnam. For this reason, the MAAG was retained as a separate headquarters.
In March 1962 Headquarters, U.S. Army, Pacific, removed the "provisional" designation from the U.S. Army Support Group, Vietnam, attached it to U.S. Army, Ryukyu Islands, for administrative and logistical support, and made its commanding officer the deputy Army component commander under MACV. In turn, all U.S. Army units in Vietnam (excluding advisory attachments) were assigned to the Army Support Group for administrative and logistical needs. Over the course of 1962 U.S. military strength in Vietnam rose from about 1,000 to over 11,000 personnel, though each service continued to provide its own logistical support.
Throughout 1963 the duties of the U.S. Army Support Group steadily increased, particularly regarding to combat support activities and logistics. During the year, the U.S. buildup continued, especially in aviation, communications, intelligence, special warfare, and logistic units, reaching a total or 17,068 man, or which 10,916 were Army. Because of this expansion, General Stilwell late in 1963 proposed that the name of the support group be changed to U.S. Army Support Command, Vietnam. General Harkins concurred and General Collins and Admiral Fell approved the redesignation. The new designation went into effect on 1 March 1964.
MACV was reorganized on 15 May 1964, and absorbed MAAG Vietnam within it, when combat unit deployment became too large for advisory group control. A Naval Advisory Group was established, and the Commanding General, 2nd Air Division, became MACV's Air Force component commander. That year the U.S. strength in Vietnam grew from about 16,000 men (10,716 Army) to about 23,300 (16,000 Army) in 1964 though logistic support operations were highly fragmented. As a result, the 1st Logistics Command was established.
Large scale combat deployments began when the 9th Marine Expeditionary Brigade was deployed in the Da Nang area from March 1965. When the III Marine Amphibious Force moved to Da Nang on 6 May 1965, its commanding general, Major General William R. Collins, USMC, was designated MACV's naval component commander. In May 1965, the Army's 173d Airborne Brigade from Okinawa arrived. In July 1965, in response to the growing size of U.S. Army forces in the country, United States Army Vietnam was established, and both the 2nd Brigade, 1st Infantry Division as well as the 1st Brigade, 101st Airborne Division, deployed from the United States. The brigade from the 101st Airborne Division was originally planned to replace the 173d Airborne Brigade but, with the need for additional combat forces, both brigades remained in Vietnam. Two months later, the 1st Cavalry Division (Airmobile), recently reorganized from an infantry formation, reported in country, and the rest of the 1st Infantry Division arrived in October.
Two corps-level HQs were established in 1965-66, Task Force Alpha (soon to become I Field Force, Vietnam) for U.S. forces in the II Corps Tactical Zone, and II Field Force, Vietnam, for U.S. Army forces in the III Corps Tactical Zone (p.52-54). The 5th Special Forces Group was also established in-country by 1965. A brigade of the 25th Infantry Division arrived in late 1965, with the 4th Infantry Division deploying between August and November 1966.
The 11th Armored Cavalry Regiment was alerted for assignment to Southeast Asia on 11 March 1966, and was later commanded there by Colonel George Patton IV.
In April 1967, General Westmoreland, who had arrived in June 1964 as Commander of MACV, organized a division-sized blocking force along the border between North and South Vietnam. The deployment of a division-sized U.S. Army force would allow the 3rd Marine Division to move north, to provide greater support for the 1st Marine Division in the northern portion of the I Corps Tactical Zone. Designated as Task Force Oregon, it included the 196th Infantry Brigade; the 3rd Brigade, 25th Infantry Division at Chu Lai; and the 1st Brigade, 10lst Airborne Division. On 25 September 1967 the new Americal Division (technically, the 23rd Infantry Division) was activated to control the blocking force, replacing the provisional task force HQ. With the elapse of five months, all the three same brigades remained in the new division, but the brigade at Chu Lai was now named the 3rd Brigade, 4th Infantry Division, after a responsibility swap that had occurred in August.
In April 1966, all Army communications-electronics resources in Vietnam were combined in a single formation, the 1st Signal Brigade. It supported the combat signal battalions of the divisions and field forces in each corps area. Additionally, the 1st Signal Brigade operated the many elements of the Defense Communications System in Vietnam. To improve co-ordination and management of communications-electronics assets, the brigade commander also served as the U.S. Army, Vietnam, staff adviser on all matters pertaining to Army communications-electronics. 
Naval Forces, Vietnam.
In contrast to the carrier, amphibious, and naval gunfire support forces and, at least during early 1965, the coastal patrol force, which Commander Seventh Fleet directed, the Navy's forces within South Vietnam were operationally controlled by COMUSMACV. Initially, General William C. Westmoreland exercised this command through the Chief, Naval Advisory Group. However, the increasing demands of the war required a distinct operational rather than an advisory headquarters for naval units. As a result, on 1 April 1966, Naval Forces, Vietnam, was established to control the Navy's units in the II, III, and IV Corps Tactical Zones. This eventually included the major combat formations: Coastal Surveillance Force (Task Force 115), River Patrol Force (Task Force 116), and Riverine Assault Force (Task Force 117). The latter unit formed the naval component of the joint Army-Navy Mobile Riverine Force.
Commander Naval Forces, Vietnam (COMNAVFORV) also controlled the Naval Support Activity Saigon (NSA Saigon), which supplied naval forces in the II, III, and IV Corps areas. Naval Support Activity Danang (NSA Danang), provided logistic support to all American forces in the I Corps area of responsibility, where the predominant Marine presence demanded a naval supply establishment. NSA Danang was under the operational control of Commander III Marine Amphibious Force.
MACV component commands.
Major component commands of MACV were:
Commanders.
The "Commander, U.S. Military Assistance Command, Vietnam" was known by the abbreviation COMUSMACV ( "com-U.S.-mack-vee"). COMUSMACV was in one sense the top person in charge of the U.S. military on the Indochinese peninsula; however, in reality, the CINCPAC and the U.S. ambassadors to Vietnam, Laos, and Cambodia also had "top person in charge" status with regard to various aspects of the war's strategy.
Inactivation.
Under the terms of the Paris Peace Accords MACV and all American and third country forces had to be withdrawn from South Vietnam within 60 days of the ceasefire. A small U.S. military headquarters was needed to continue the military assistance program for the southern Republic of Vietnam Military Forces and supervise the technical assistance still required to complete the goals of Vietnamization. This headquarters was to become the Defense Attaché Office, Saigon. That headquarters was also to report operational and military intelligence through military channels to DOD authorities. In addition a multi-service organization was required to plan for the application of U.S. air and naval power into North or South Vietnam, Cambodia or Laos, should this be required and ordered. Called the United States Support Activities Group & 7th Air Force (USSAG/7th AF), it was to be located at Nakhon Phanom Royal Thai Air Force Base in northeast Thailand.
The advance echelon of USSAG/7AF moved from Tan Son Nhut Air Base to Nakhon Phanom on 29 January 1973. Transfer of the main body, drawn largely from the operations and intelligence sections of MACV and Seventh Air Force, began on 10 February. USSAG was activated on 11 February 1973 under the command of commander of MACV, but at 08:00 on 15 February, USAF General John W. Vogt Jr., as USSAG/7AF commander, took over from MACV control of American air operations. U.S. air support operations into Cambodia continued under USSAG/7th AF until August 1973.
The DAO was established as a subsidiary command of MACV and remained under the command of commander of MACV until the deactivation of MACV on 27 March 1973 at which time command passed to the Commander USSAG/Seventh Air Force at Nakhon Phanom. The DAO was activated on 28 January 1973 with United States Army Major General John E. Murray, formerly MACV director of logistics, as the Defense Attaché and United States Air Force Brigadier General Ralph J. Maglione, formerly the MACV J-1 (Director for Manpower and Personnel), as deputy Defense Attaché.
By 29 March, the only American military personnel left in South Vietnam were the U.S. delegates to the Four-Party Joint Military Commission established under the Paris Peace Accords to oversee the ceasefire, themselves in the process of winding up work and departing; the fifty man DAO military contingent; and a 143-man Marine Security Guard. At 11:00 on the 29th, in a simple ceremony, General Weyand furled the colors of the Military Assistance Command, Vietnam, and formally inactivated it.
MACV Headquarters/DAO Compound.
The original MACV Headquarters were colocated with MAAG at 606 Trần Hưng Đạo, Cholon, but in May 1962 were moved to 137 Pasteur Street () in central Saigon. The Trần Hưng Đạo site subsequently became the headquarters of Republic of Korea armed forces in Vietnam.
As the US military presence in South Vietnam grew, MACV quickly outgrew these quarters and on 2 July 1966 construction of a new purpose-built facility () adjacent to Tan Son Nhut Airport and the ARVN Joint General Staff Compound was commenced. Due to the size of this facility, the new headquarters were labelled Pentagon East. The building was designed and constructed under the supervision of the U.S. Navy Officer in Charge of Construction RVN. The construction contractor was RMK-BRJ at a cost of $28 million.
Following the closure of MACV and the establishment of the DAO, the MACV Headquarters became the DAO Compound.