What was the Vietnam War? Causes, course and legacy

The Vietnam War was a war over who would rule Vietnam, fought from about 1955 to 1975 between communist North Vietnam, with its allies in the South, and the government of South Vietnam, backed by the United States. It grew out of the end of French colonial rule and became a front of the Cold War. It ended on 30 April 1975, when North Vietnamese tanks entered Saigon and the country was reunited under communist rule.

In short

• It was two wars at once: a Vietnamese civil war and independence struggle, and a Cold War contest in which the United States tried to stop communism spreading.
• American involvement grew from advisers in the 1950s to more than 500,000 troops by 1968, then shrank after the Tet Offensive turned US opinion.
• The toll fell mostly on the Vietnamese: estimates run from under 1 million to more than 3 million dead, against 58,220 Americans.

Where did the war come from?

Vietnam was part of French Indochina from the late 19th century. During World War II Japan occupied it, and a communist-led independence movement, the Viet Minh, under Ho Chi Minh, organized against both. On 2 September 1945 Ho declared Vietnam independent. France fought to take its colony back, and the First Indochina War lasted until 1954, when the Viet Minh overran the French base at Dien Bien Phu.

The peace conference at Geneva in 1954 divided Vietnam at the 17th parallel, as a temporary line: Ho's government in the North, a non-communist state in the South, and nationwide elections promised for 1956. The elections never happened. South Vietnam's leader, Ngo Dinh Diem, refused them, and the United States, which expected Ho to win, supported him. The Office of the Historian notes that France had fought with US financial help, and that the United States did not sign the Geneva agreement that called for the elections.

Why did a country so far away matter to Washington? American leaders saw Vietnam through the "domino theory": if one country in Southeast Asia fell to communism, its neighbors would follow. Vietnam had become part of the global rivalry of the Cold War, with the Soviet Union and China arming the North.

How did the United States get drawn in?

Step by step, each step meant to avoid a bigger one. From the late 1950s, southern communists and their allies, the National Liberation Front, which the US and Saigon called the Viet Cong, fought a growing insurgency against Diem's government, supplied from the North along the Ho Chi Minh Trail through Laos and Cambodia. By 1963 there were about 16,000 American military advisers in the South. That November, Diem was overthrown and killed in a coup the US had signaled it would not oppose.

The turning point came in August 1964. US destroyers in the Gulf of Tonkin reported attacks by North Vietnamese boats on 2 August and again on 4 August. Congress passed the Gulf of Tonkin Resolution on 7 August, unanimously in the House and with two votes against in the Senate, letting President Lyndon Johnson use force without declaring war. Doubts later emerged about whether the second attack happened at all, the State Department's historians note. In March 1965 Johnson began a sustained bombing campaign of the North and sent the first combat Marines.

How did the war unfold?

Year	What happened
1954	French defeat at Dien Bien Phu; Geneva divides Vietnam
1964	Gulf of Tonkin Resolution
1965	Bombing of the North begins; US combat troops arrive
1968	Tet Offensive, January; My Lai massacre, March; US deaths peak
1969	US troops peak at about 543,000; withdrawals begin
1970	US and South Vietnamese forces enter Cambodia; protests at home
1973	Paris peace agreement signed 27 January; last US combat troops leave in March
1975	North Vietnamese offensive; Saigon falls 30 April
1976	Vietnam formally reunited as the Socialist Republic of Vietnam

The US fought a war of attrition: find the enemy, kill more than could be replaced, and count bodies to measure progress. The North and the National Liberation Front could absorb losses and choose when to fight, in jungle and villages where guerrillas and civilians were hard to tell apart.

On 30 January 1968, during the Vietnamese New Year, Tet, communist forces attacked more than 100 towns and cities across the South at once, even reaching the US embassy compound in Saigon. Militarily it failed, at a terrible cost to the attackers. Politically it was decisive. After years of official assurances that the war was being won, Americans saw that it was not close to over. Johnson announced in March that he would not run again. 1968 was the deadliest year for Americans, with 16,899 deaths in the National Archives' records.

His successor, Richard Nixon, pursued "Vietnamization": withdrawing US troops while building up South Vietnam's army to fight alone. He also widened the war into Cambodia and Laos and bombed the North heavily. The United States and North Vietnam signed a peace agreement in Paris on 27 January 1973, and the last US combat troops left that March. Without them, South Vietnam held out for two years. In spring 1975 the North launched a final offensive, and Saigon fell on 30 April.

How many people died?

Counts of Vietnamese dead differ widely, depending on the years covered, whether Laos and Cambodia are included, and who did the counting.

Group	Estimate	Source
US military	58,220	US National Archives
South Vietnamese military	about 170,000 to 313,000	estimates by Guenter Lewy, Jeffrey Clarke and R. J. Rummel
North Vietnamese and NLF fighters	about 1.1 million (1955–1975)	Vietnamese government, 1995
Vietnamese civilians, both sides	about 2 million (1955–1975)	Vietnamese government, 1995
All Vietnamese war deaths, 1965–1975	791,000 to 1,141,000	demographic study by Charles Hirschman and colleagues, 1995

So the war killed somewhere between about 800,000 and more than 3 million Vietnamese, and hundreds of thousands more died in Cambodia and Laos. For every American who died, at the low end of the estimates, more than 13 Vietnamese did. Millions more were wounded or displaced, and unexploded bombs and the herbicide Agent Orange, sprayed by US forces to strip forest cover, went on harming people for decades.

What did the war leave behind?

In Vietnam, the war is known as the Resistance War against America, and it is remembered as the end of a long struggle for independence and unity. Reunification was followed by hardship: former southern officials and soldiers, tens of thousands to hundreds of thousands by different estimates, were sent to "re-education" camps, and from the late 1970s hundreds of thousands of "boat people" fled by sea. Vietnam opened its economy from 1986, and it restored diplomatic relations with the United States in 1995.

In the United States, the war broke trust in government. The Pentagon Papers, published in 1971, showed that officials had privately doubted the war while publicly promising success. Congress passed the War Powers Resolution in 1973 to limit a president's power to commit troops without its approval, and the draft ended the same year. Veterans came home to a divided country, and the war's lessons, about the limits of military power and about entering wars step by step, are still argued over, as are all wars in how historians weigh the past.

Still argued

Historians still argue whether the war could have been won. One school holds that it was unwinnable, a nationalist revolution the US misread as Soviet or Chinese expansion. Another, often called revisionist, argues that South Vietnam was viable and that the US lost by fighting the wrong kind of war or abandoning its ally after 1973. The evidence settles the course of events; it can't settle the counterfactual.

Check yourself

• Without looking back: why did the 1954 Geneva settlement leave Vietnam divided, and why were the promised elections never held?
• How could the Tet Offensive be a military defeat for the North and still change the war's outcome?
• Why do estimates of Vietnamese deaths range so widely?

Sources

• Dien Bien Phu and the fall of French Indochina, 1954 — Office of the Historian, U.S. Department of State
• U.S. involvement in the Vietnam War: the Gulf of Tonkin and escalation, 1964 — Office of the Historian, U.S. Department of State
• Ending the Vietnam War, 1969–1973 — Office of the Historian, U.S. Department of State
• Vietnam War U.S. military fatal casualty statistics — U.S. National Archives
• Vietnam War casualties — Wikipedia