Vietnam War (1955–1975): Causes, Course and Consequences

The Vietnam War was a long conflict fought from the mid-1950s to 1975 between communist North Vietnam, with its southern allies the Viet Cong, and the government of South Vietnam, backed above all by the United States. It grew from a struggle over Vietnam’s independence and unity into one of the bloodiest wars of the Cold War, with up to half a million American troops deployed at its peak. The war ended with the fall of Saigon on 30 April 1975 and the reunification of Vietnam under communist rule.

Background: from colony to partition

Vietnam had been part of French Indochina since the late 19th century. During the Second World War Japan occupied the region, and the communist-led Viet Minh, headed by Ho Chi Minh, organised resistance. On 2 September 1945 Ho declared the independence of the Democratic Republic of Vietnam in Hanoi.

France returned to reclaim its colony, and the First Indochina War broke out in 1946. As the Cold War deepened and communists won in China in 1949, the United States came to see the conflict as part of a global struggle against communism and paid an increasing share of France’s war costs.

The French defeat at the Battle of Dien Bien Phu in May 1954 ended the war. The Geneva Accords of July 1954 temporarily divided Vietnam at the 17th parallel, with the Viet Minh in the North and the French-backed State of Vietnam in the South, and called for nationwide elections in 1956.

Two Vietnams, 1954–1963

In the South, the anti-communist Catholic nationalist Ngo Dinh Diem became prime minister in 1954. In October 1955 he deposed the former emperor Bao Dai in a rigged referendum and proclaimed the Republic of Vietnam, with himself as president. Diem, supported by the United States, refused to hold the 1956 elections, which most observers expected Ho Chi Minh to win.

On 1 November 1955 the US Military Assistance Advisory Group, Vietnam, was formally established to train South Vietnam’s army. The US Department of Defense later adopted this date as the official start of the conflict, and it is the date used for the Vietnam Veterans Memorial.

Diem’s rule was authoritarian, and his repression of former Viet Minh and other opponents fuelled armed resistance in the countryside. In 1959 North Vietnam’s leadership decided to support armed struggle in the South and began developing supply routes that became the Ho Chi Minh Trail. In December 1960 the National Liberation Front (NLF), known to its enemies as the Viet Cong, was founded.

President John F. Kennedy expanded American support, raising the number of US military advisers from under 1,000 to about 16,000 by late 1963. Diem’s government grew increasingly unpopular, especially after its crackdown on Buddhist protests in 1963, which drew world attention when the monk Thich Quang Duc burned himself to death in Saigon. On 1 November 1963 South Vietnamese generals overthrew Diem, with the knowledge of US officials, and he was killed the next day.

American escalation, 1964–1968

After Diem’s death South Vietnam went through a series of unstable military governments, and the Viet Cong gained ground. In August 1964 reports of attacks on US destroyers in the Gulf of Tonkin led Congress to pass the Gulf of Tonkin Resolution, giving President Lyndon B. Johnson broad authority to use military force.

In March 1965 Johnson began a sustained bombing campaign against North Vietnam, Operation Rolling Thunder, and the first US Marine combat battalions landed at Da Nang. American troop numbers rose rapidly, from about 23,000 at the end of 1964 to more than 180,000 by the end of 1965 and around 536,000 by the end of 1968. The peak, about 543,000, came in April 1969.

The US commander, General William Westmoreland, pursued a strategy of attrition, using “search and destroy” operations and massive firepower to kill enemy soldiers faster than they could be replaced. Helicopters gave American forces great mobility, as in the Battle of Ia Drang in November 1965. North Vietnam, under leaders including Le Duan and General Vo Nguyen Giap, received weapons and aid from the Soviet Union and China and was prepared to accept enormous losses.

South Korea, Australia, New Zealand, Thailand and the Philippines also sent troops to support South Vietnam, with South Korea’s contingent the largest.

The Tet Offensive and the turn

On 30 and 31 January 1968, during the Tet lunar new year holiday, communist forces launched surprise attacks on more than 100 cities and towns across South Vietnam, including the US embassy compound in Saigon. In the old imperial capital of Hue fighting lasted almost a month, and thousands of civilians were killed, many of them executed by communist forces.

Militarily, the Tet Offensive was a heavy defeat for the Viet Cong, which lost many of its best cadres. Politically, however, it shocked the American public, which had been told that the war was being won. In March 1968, the same month that US soldiers killed several hundred unarmed villagers at My Lai, Johnson announced a partial halt to the bombing and said he would not seek re-election. Peace talks opened in Paris in May 1968.

Withdrawal and the fall of the South, 1969–1975

Richard Nixon, elected president in November 1968, introduced “Vietnamisation”: building up South Vietnam’s forces while gradually withdrawing American troops. At the same time he widened the war, secretly bombing Cambodia from 1969 and sending US and South Vietnamese troops into Cambodia in 1970, which set off huge protests in the United States, including the shootings at Kent State University in May 1970.

Opposition to the war had grown since the mid-1960s, through campus protests, the draft resistance movement and veterans’ groups. The publication of the Pentagon Papers in 1971, a secret government history of the war, deepened distrust of official claims.

In spring 1972 North Vietnam launched the Easter Offensive, a conventional invasion that was halted mainly by American air power. After talks stalled, Nixon ordered the intense bombing of Hanoi and Haiphong in December 1972, known as Linebacker II. The Paris Peace Accords were signed on 27 January 1973, and the last US combat troops left South Vietnam on 29 March 1973. American prisoners of war were returned, but North Vietnamese troops were allowed to remain in the South.

The ceasefire soon broke down. The US Congress, reacting against the war and absorbed by the Watergate scandal, cut aid to South Vietnam and passed the War Powers Resolution in 1973. In March 1975 North Vietnam launched a major offensive in the Central Highlands. South Vietnamese forces collapsed in a chaotic retreat, and Hue and Da Nang fell within weeks.

As North Vietnamese troops approached Saigon, the United States carried out a last-minute helicopter evacuation of Americans and thousands of Vietnamese from the city. On 30 April 1975 North Vietnamese tanks broke through the gates of the Presidential Palace and South Vietnam surrendered (see Fall of Saigon). Vietnam was formally reunified as the Socialist Republic of Vietnam on 2 July 1976. In the same month that Saigon fell, the Khmer Rouge captured Phnom Penh in Cambodia, and communists took power in Laos later in 1975.

Human cost

The war’s toll was immense, and many figures are estimates.

The United States dropped millions of tons of bombs across Indochina, more than all the bombs it dropped in the Second World War. Large areas were sprayed with herbicides such as Agent Orange, whose health effects remain disputed and painful issues in Vietnam and among veterans. Unexploded ordnance continues to kill and injure people in Vietnam, Laos and Cambodia.

Consequences and legacy

After 1975 hundreds of thousands of South Vietnamese were held in re-education camps, and from the late 1970s large numbers of refugees, known as “boat people”, fled by sea, many dying on the way. Vietnam invaded Cambodia in 1978 to overthrow the Khmer Rouge and fought a short border war with China in 1979. Economic reforms known as Doi Moi began in 1986, and the United States and Vietnam normalised relations in 1995.

In the United States the war left deep divisions. It weakened public trust in government, ended the military draft in 1973 and produced the “Vietnam syndrome”, a reluctance to commit ground troops abroad. The Vietnam Veterans Memorial in Washington, D.C., dedicated in 1982, lists the names of more than 58,000 Americans who died.

Myths and facts

A common belief is that American forces were defeated on the battlefield. In fact they won most large engagements; the war was lost politically, because the US could not create a South Vietnamese state able to stand on its own and because the American public would not support an open-ended war.

Another claim is that the second Gulf of Tonkin attack on 4 August 1964 clearly took place. Later research, including a declassified history by the US National Security Agency, concluded that no attack occurred that night, although the first clash on 2 August was real.

Timeline

• 1954, 7 May: French forces surrender at Dien Bien Phu.
• 1954, 21 July: The Geneva Accords divide Vietnam at the 17th parallel.
• 1955, 1 November: The US Military Assistance Advisory Group, Vietnam, is established.
• 1960, 20 December: The National Liberation Front is founded.
• 1963, 2 November: Ngo Dinh Diem is killed after a coup.
• 1964, 7 August: Congress passes the Gulf of Tonkin Resolution.
• 1965, 8 March: US Marines land at Da Nang.
• 1968, 30–31 January: The Tet Offensive begins.
• 1973, 27 January: The Paris Peace Accords are signed.
• 1975, 30 April: Saigon falls to North Vietnamese forces.

Why it matters

The Vietnam War reshaped Southeast Asia, reunified Vietnam and left millions dead, wounded or displaced. For the United States it was the first war it clearly failed to win, a turning point that changed its politics, military and culture. It remains a central case study in the limits of military power, the role of public opinion in war and the costs of Cold War intervention.