No single incident marked the beginning of the American war in Vietnam, though several watershed moments passed between the 1954 defeat of the French occupying force and the negotiated end of hostilities in 1973. The 1954 Geneva agreement, which ended the French presence in Indochina, called for a referendum on the form of government Vietnam would adopt in 1956. The United States cancelled the vote, and hostilities began.
Throughout the 1950s, hostilities manifested at a relatively low level, and American forces were deployed in roles that were officially advisory only. Increasingly, however, American forces took on more direct roles in combating the influence of the Communist-led resistance. In 1960, the Vietcong formed to unify anti-American factions in South Vietnam. In 1962, President Kennedy authorized a large-scale bombing campaign against targets in South Vietnam. Two days after President Kennedy's death, President Johnson publicly renewed his determination to fight in Vietnam.
In 1964, the USS Maddox reported suffering a night attack by North Vietnamese gunboats in the Gulf of Tonkin. The U.S. Congress responded by voting to give what amounted to war powers to the president. American combat forces were then deployed in large numbers to South Vietnam for the first time, and operations intensified against the Vietcong.