Vietnam War

War from 1954 to 1975 between communist North Vietnam and US‐backed South Vietnam, in which North Vietnam aimed to conquer South Vietnam and unite the country as a communist state. North Vietnam was supported by communist rebels from South Vietnam, the Vietcong. The USA, in supporting the South against the North, aimed to prevent the spread of communism in Southeast Asia, but at the end of the war North and South Vietnam were reunited as a socialist republic.

Following the division of French Indochina into North and South Vietnam and the Vietnamese defeat of the French in 1954, US involvement in Southeast Asia grew through the Southeast Asia Treaty Organization (SEATO) pact. Non‐communist South Vietnam was viewed, in the context of the 1950s and the Cold War, as a bulwark against the spread of communism throughout Southeast Asia. Advisers and military aid were dispatched to the region at increasing levels because of the so‐called domino theory, which contended that the fall of South Vietnam would precipitate the collapse of neighbouring states. The USA spent $141 billion on aid to the South Vietnamese government, but corruption and inefficiency led the USA to assume ever greater responsibility for the war effort, until 1 million US combat troops were engaged.

In the USA, the draft, the high war casualties, the use of toxins such as napalm and Agent Orange, and the undeclared nature of the war resulted in growing domestic resistance, which caused social unrest and forced President Lyndon Johnson to abandon re‐election plans (see Vietnam War protests). President Richard Nixon first expanded the war to Laos and Cambodia but finally phased out US involvement; his national security adviser Henry Kissinger negotiated a peace treaty in 1973 with North Vietnam, which soon conquered South Vietnam and united the nation.

Some 200,000 South Vietnamese soldiers, 1 million North Vietnamese soldiers, and 500,000 civilians were killed; 56,555 US soldiers were killed 1961–75. The war destroyed 50% of the country's forest cover and 20% of agricultural land. Cambodia, a neutral neighbour, was bombed by the USA 1969–75, with 1 million killed or wounded. Although US forces were never militarily defeated, Vietnam was considered a humiliating political defeat for the USA.

Following the Geneva agreement of 1954, there were five years of relative calm until 1959, when relations between North and South Vietnam again became critical. The Ngo Dinh Diem regime in Saigon tried to eliminate the remaining communists in the south, and the communist government of Ho Chi Minh in Hanoi decided to assist a new rebellion south of the 17th parallel. By the end of 1960, the anti‐Diem forces in the south had formed a national liberation front under the leadership of southern communists, and during 1961 Diem, who had depended on US aid since 1954, sought additional protection. General Maxwell Taylor went to Saigon in October 1961 and President John F Kennedy decided against sending regular combat units to Vietnam but agreed to send ‘advisers’, many of whom were units of special forces expert in covert warfare. During 1961–62, a ‘strategic hamlet program’ was initiated to improve security in the countryside, based on ideas borrowed from the British campaign against insurgents in Malaya. By the time of Kennedy's death in November 1963 there were about 16,700 US troops in South Vietnam, and the situation was still far from under control. The main consequence of greater US involvement was that the north gave even more help to the Vietcong.

During 1963 growing unrest against Ngo Dinh Diem led to more stringent repression culminating in a Buddhist rebellion May–August which caused the US government serious political embarrassment. Fearing that they would be accused of backing a dictatorship, they eventually decided to remove Ngo Dinh Diem. He was deposed by a military coup in November 1963 and a committee of generals took over South Vietnam. Their regime proved even less satisfactory to the USA however, and 1964 saw a mounting political crisis in Saigon.

During 1963 President Kennedy had planned to start reducing the US commitment, on the basis of optimistic reports that communist ‘insurgency’ would be defeated by the end of 1965. After Kennedy's death, President Johnson adopted a less cautious approach and during the course of 1964 allowed the preparation of plans for both covert operations and open air warfare against North Vietnam on the grounds that the latter was the real instigator of the war in the south. Despite his emphasis on peace during an election campaign against the more hawkish Senator Barry Goldwater, by the end of the year Johnson was virtually committed to escalation of the Vietnam conflict. After the Tonkin Gulf Incident of August 1964, in which the US Navy claimed that two of its ships were attacked by North Vietnamese patrol boats, Johnson secured from Congress a resolution which he later interpreted as allowing him to take unlimited action to resolve the crisis in Southeast Asia.

By early 1965 the communist guerrilla operations in the south were being dramatically stepped up. An attack on a US base at Pleiku in February 1965 was used as the justification for starting air attacks on the north, which were to be a daily feature of the war until 1968. The USA began sending in combat troops to Vietnam in April 1965, and their numbers increased steadily until March 1968. The political crisis in Saigon was eased with the emergence of Nguyen Cao Ky as prime minister (1965–67), the establishment of a new constitution in 1966, and the election of Nguyen Van Thieu as president in 1967. But the war situation became even more serious as US and South Vietnamese forces failed either to suppress the national liberation front in the south, or to destroy the determination of the leaders in Hanoi to drive the Americans out.

US resolve was seriously shaken in February 1968 by the Tet Offensive, in which the communist Vietcong guerrillas initiated major battles in Saigon, Hué, and a number of other towns. A crisis was reached in March 1968 when the US commander General William Childs Westmoreland asked for another 200,000 troops to go to Vietnam, on top of the 550,000 US personnel already there. By this time there were also Korean and Australian contingents deployed in Vietnam on top of the 400,000 South Vietnamese under arms. Faced with a serious monetary crisis at the same time, as well as strong domestic opposition to the war, President Johnson decided against sending any more troops to Vietnam and announced a limitation of bombing raids on the north. Before the end of 1968 the bombing had been halted completely and peace talks had opened in Paris; the USA then began to reduce its ground forces in Vietnam. But the war dragged on throughout 1969–71 and spread throughout the region. In an attempt to protect the still fragile situation in South Vietnam, President Nixon spread the war to Cambodia: he secured the removal of Prince Norodom Sihanouk's neutral regime in Phnom Penh and began the heavy bombing of Cambodia which drew that country into the conflict and ultimately resulted in the Khmer Rouge government coming to power. Heavy fighting also erupted in Laos at the same time, so that the war once again engulfed the whole of Indochina.

Anxious to break the stalemate, North Vietnam launched a new and much heavier offensive against the South Vietnamese army in Quang Tri province and in the region of An Loc (north of Saigon) in the spring of 1972. There were now fewer than 100,000 US troops in Vietnam and so the USA responded with intense bombing of the north, the mining of Haiphong harbour, and unlimited air support for South Vietnamese ground troops. This held the situation, but it became clear that it was only temporary.

Increased contacts between Hanoi and Washington during 1972 led eventually to the signing of the Paris Peace Accord in January 1973 by South Vietnam, North Vietnam, the Vietcong, and the USA. Just prior to this ceasefire agreement, in December 1972, a last bout of aerial bombardment against Hanoi was carried out, effectively destroying the north's capacity for a further offensive for the next two years.

US forces finally left South Vietnam in March 1973, and for two years the South Vietnamese government of Nguyen Van Thieu sought to continue the US policy of pacification. But the Vietcong provisional revolutionary government of South Vietnam was making substantial political gains in the countryside and in late 1974 North Vietnam breached the ceasefire with a final offensive against the south. By March 1975 South Vietnamese morale had collapsed, and in April the communist forces took Saigon with only a limited amount of fighting. The remaining Americans hastily evacuated Saigon by helicopter and several thousand Vietnamese refugees also fled the country. Vietnam was reunited as the Socialist Republic of Vietnam in July 1976.