U.S. Army in Vietnam
The U.S. Army in Vietnam, 1954-1973
The Communists’ victory at Dien Bien Phu in May 1954 marked the end of French involvement in Indochina. The Geneva Accords of July 1954 divided Vietnam into a Communist state in the North and an anti-Communist state in the South.
The United States had supported the French army in Indochina through the Military Assistance Advisory Group (MAAG), and U.S. advisers continued to train and organize the South Vietnamese Army to repel an invasion from the North. In 1955, MAAG numbered 342 officers and men--most of them Army personnel—rising to around 700 by 1960. In February 1962, the Joint Chiefs of Staff established the U.S. Military Assistance Command, Vietnam (MACV), appointing General Paul D. Harkins as the first commander. General William C. Westmoreland succeeded Harkins in June 1964. As MACV’s responsibilities expanded, U.S. military strength in South Vietnam increased to 23,000 by the end of 1964. Of these, about 15,000 were Army personnel.
Composite_Chopper_RunIn 1965, President Lyndon B. Johnson began sending U.S. ground troops to stave off the defeat of the South Vietnamese Army. At first, Army combat units played a defensive role, protecting Saigon, the South Vietnamese capital, and other important cities and bases. The president authorized the Army to send 20,000 support troops to establish a supply network that had to be built from the ground up. The newly formed U.S. Army, Vietnam managed the logistical effort.
As the U.S. troop presence increased, Army combat units operated farther afield. In the fall of 1965, Westmoreland sent the 1st Cavalry Division—the Army’s first airmobile unit—to the rugged Central Highlands, where it defeated North Vietnamese regulars in the month-long Battle of the Ia Drang.
By the fall of 1966, Westmoreland had enough forces, including 240,000 soldiers, to mount sustained offensives. For over a year, Army combat units conducted search and destroy operations against an elusive enemy. Whenever the Army could bring its superior firepower to bear, the results were often devastating. On 10 March 1967, a Viet Cong regiment mounted a night assault on Firebase Prek Klok, defended by a battalion of the 1st Infantry Division, resulting in 200 enemy dead at a cost of 3 U.S. fatalities.
On 31 January 1968, the Communists launched a major assault known as the Tet Offensive. U.S. Army units helped to repel Viet Cong attacks at Saigon and other South Vietnamese cities. The fiercest battle occurred around Hue, where soldiers of the 1st Cavalry Division and the 101st Airborne Division helped U.S. marines and South Vietnamese forces defeat North Vietnamese regulars. Although a tactical victory, Tet signaled a change in U.S. policy in Vietnam; henceforth, peace negotiations would play a pivotal role in ending the war.
In 1969, President Richard M. Nixon introduced a program called Vietnamization, in which the South Vietnamese Army assumed an ever-larger combat role, as MACV began a phased withdrawal of over half a million U.S. soldiers and marines. Westmoreland’s successor, General Creighton W. Abrams, continued search and destroy operations, gradually reducing their frequency as the drawdown progressed. Notwithstanding their diminishing numbers, Army units and advisers supported South Vietnamese forces in the Cambodian Campaign (1970), Operation LAM SON 719 (1971) in Laos, and in the repulse of the enemy’s Easter Offensive (1972). The Army’s role in the Vietnam War officially ended on 29 March 1973, with a ceremony marking the deactivation of MACV.                        
Source: Center for Military History