1965–29 March 1973: U.S. Full Military Engagement

In 1965, the United States transformed its involvement in Vietnam from an advisory mission into a major combat commitment. President Lyndon Johnson authorized Operation Rolling Thunder, a sustained bombing campaign against North Vietnam, beginning in March. On March 8, U.S. Marines landed at Da Nang to protect the airbase. Their arrival marked the introduction of American ground combat units, followed by deployments that expanded their mission from security to offensive operations.


General William Westmoreland directed a strategy intended to wear down communist forces through superior mobility, firepower, and sustained combat. American troops conducted search-and-destroy operations against North Vietnamese regulars and Viet Cong guerrillas. Helicopters moved soldiers rapidly, while artillery and aircraft supported ground operations. The fighting at Ia Drang in November 1965 demonstrated both the effectiveness of American firepower and the enemy’s determination to withstand heavy losses.


The American commitment grew dramatically, reaching approximately 543,000 military personnel in 1969. Soldiers fought in jungles, rice paddies, mountains, and cities, often facing ambushes, mines, and an elusive enemy. Naval forces patrolled coastal waters and rivers, while aircrews attacked military targets and supply routes. Pacification efforts sought to strengthen South Vietnamese government control. Nevertheless, battlefield successes did not consistently produce lasting security, and civilians suffered deaths, displacement, and destruction.


In January 1968, communist forces launched the Tet Offensive, striking cities and installations throughout South Vietnam. American and South Vietnamese troops eventually repelled the attacks, inflicting heavy enemy losses. Yet the offensive undermined assurances that victory was approaching. Fighting in Hue and the siege of Khe Sanh became defining episodes. Growing casualties, television coverage, and controversy deepened divisions within the United States. Johnson limited bombing and announced that he would not seek reelection.


President Richard Nixon took office in 1969 and introduced Vietnamization, gradually transferring combat responsibilities to South Vietnamese forces while withdrawing American troops. General Creighton Abrams emphasized strengthening those forces and improving local security. Withdrawal, however, occurred alongside continued fighting and expanded air operations. American and South Vietnamese forces entered Cambodia in 1970, provoking widespread protests. In 1971, South Vietnamese troops advanced into Laos with American aviation support but suffered serious losses.


North Vietnam’s 1972 Easter Offensive tested Vietnamization. South Vietnamese defenders, supported by extensive American airpower, prevented a decisive communist victory. Nixon ordered the mining of northern ports and Operation Linebacker. December’s Linebacker II bombing campaign followed stalled negotiations. Diplomacy and military pressure culminated in the Paris Peace Accords, signed January 27, 1973, providing for a ceasefire, American withdrawal, and the release of prisoners of war.


On March 29, 1973, the remaining U.S. troops covered by the withdrawal agreement departed, and Military Assistance Command, Vietnam, was dissolved. A small military contingent remained for diplomatic security and defense support. America’s major combat commitment in Vietnam had ended, leaving profound losses and lasting consequences. Fighting between the Vietnamese sides continued, despite the peace agreement, until South Vietnam’s collapse in April 1975.

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