American involvement in the Vietnam War began during the postwar period of decolonization. The Soviet Union backed many nationalist movements across the globe, but the United States feared the expansion of communist influence and pledged to confront any revolutions aligned against Western capitalism. The Domino Theory—the idea that if a country fell to communism, then neighboring states would soon follow—governed American foreign policy. After the communist takeover of China in 1949, the United States financially supported the French military’s effort to retain control over its colonies in Vietnam, Cambodia, and Laos.
Between 1946 and 1954, France fought a counterinsurgency campaign against the nationalist Viet Minh forces led by Ho Chi Minh. The United States assisted the French war effort with funds, arms, and advisors, but it was not enough. On the eve of the Geneva Peace Conference in 1954, Viet Minh forces defeated the French army at Dien Bien Phu. The conference temporarily divided Vietnam into two separate states until UN-monitored elections occurred. But the United States feared a communist electoral victory and blocked the elections. The temporary partition became permanent. The United States established the Republic of Vietnam, or South Vietnam, with the U.S.-backed Ngo Dinh Diem as prime minister. Diem, who had lived in the United States, was a committed anticommunist.
Diem’s government, however, and its Army of the Republic of Vietnam (ARVN) could not contain the communist insurgency seeking the reunification of Vietnam. The Americans provided weapons and support, but despite a clear numerical and technological advantage, South Vietnam stumbled before insurgent Vietcong (VC) units. Diem, a corrupt leader propped up by the American government with little domestic support, was assassinated in 1963. A merry-go-round of military dictators followed as the situation in South Vietnam continued to deteriorate. The American public, though, remained largely unaware of Vietnam in the early 1960s, even as President John F. Kennedy deployed some sixteen thousand military advisors to help South Vietnam suppress a domestic communist insurgency.16
This all changed in 1964. On August 2, the USS Maddox reported incoming fire from North Vietnamese ships in the Gulf of Tonkin. Although the details of the incident are controversial, the Johnson administration exploited the event to provide a pretext for escalating American involvement in Vietnam. Congress passed the Gulf of Tonkin Resolution, granting President Johnson the authority to deploy the American military to defend South Vietnam. U.S. Marines landed in Vietnam in March 1965, and the American ground war began.
American forces under General William Westmoreland were tasked with defending South Vietnam against the insurgent VC and the regular North Vietnamese Army (NVA). But no matter how many troops the Americans sent or how many bombs they dropped, they could not win. This was a different kind of war. Progress was not measured by cities won or territory taken but by body counts and kill ratios. Although American officials like Westmoreland and secretary of defense Robert McNamara claimed a communist defeat was on the horizon, by 1968 half a million American troops were stationed in Vietnam, nearly twenty thousand had been killed, and the war was still no closer to being won. Protests, which would provide the backdrop for the American counterculture, erupted across the country.