The French had colonised Indochina in the nineteenth century, and after losing it to the Japanese during the Second World War were able to regain it in 1945 with Japan's defeat. France soon found its position in Indochina threatened by a communist-inspired uprising, and from 1950 to 1954 the United States, concerned, as one might expect, with preventing the spread of communism while also seeking indirectly to support France's position in Europe, provided $4 billion of aid to support the French war. The Battle of Dien Bien Phu in 1954 brought an end to the French imperial presence in Indochina, which was then partitioned into North and South Vietnam, Cambodia and Laos. The North was under communist control, and, of course, the United States stepped up its presence considerably in support of South Vietnam. By 1965 American combat troops were fighting there in an anti-communist war.

This chapter explores the escalation of the American commitment under President Johnson from 1963 to 1965. Attention is given to key developments such as the Gulf of Tonkin Resolution in the summer of 1964, the initiation of a bombing campaign in Vietnam in February 1965 and the introduction of American combat troops throughout South Vietnam a few months later. There then follows an account of the various influences, potential or actual, upon the White House. These included concerns with international credibility; the ‘domino theory’; the role of advisers; public opinion in the United States; the role of allies; the regime in Saigon; and the Sino-Soviet dimension to policymaking.