In its entirety, the Vietnam War lasted thirty years, stretching from the end of World War II to the fall of South Vietnam in 1975. US military involvement began after France withdrew from its former colony following the French defeat at Dien Bien Phu in 1954. With the colonial war decided, Vietnam was divided into a communist regime in the north and an anticommunist one in the south. US military personnel at first assisted South Vietnam in a training and advising capacity in its fight against North Vietnam and communist insurgents in the south known as the Viet Cong. But the US role escalated under President Lyndon Johnson who introduced American combat troops in 1965. Troop levels, which had been under 20,000 when Johnson took office in November 1963, increased to more than 180,000 by the end of 1965; by 1968 more than half a million US servicemen and women were stationed in Vietnam.
As the United States built up its military presence, antiwar protests grew at home. On October 15, 1969, approximately one million people nationwide participated in the Vietnam War Moratorium demonstrations. On many college campuses these demonstrations took the form of student strikes, teach-in sessions, and peace rallies. In one such demonstration at the University of Missouri-Columbia, five thousand people also marched through Columbia to protest the war. The demonstrations drew counter protesters as well; in Columbia one such group, the Young Americans for Freedom, handed out pamphlets and newspapers criticizing the antiwar movement. But opposition to the war continued, particularly after the military buildup failed to bring the fighting closer to an end. During the presidency of Richard Nixon, troop levels were gradually reduced until the last combat units were withdrawn in 1973. The end of the war came two years later when North Vietnamese forces captured Saigon, the capital of South Vietnam.
Many Missourians were involved in the Vietnam War, both through military service and as civilians. Some of state's more famous participants included St. Louis-born war correspondent Martha Gellhorn, who reported the war for the British newspaper The Guardian in 1966; broadcast journalist Walter Cronkite, a native of St. Joseph whose special report from Vietnam in 1968 following the Tet Offensive is credited with helping to change national opinion about the war, and St. Louis native Thomas A. Dooley, a doctor and anticommunist activist whose 1956 best-selling book Deliver Us from Evil made an early argument for US intervention in Vietnam.