Between 1945 and 1954, the Vietnamese waged an anti-colonial war against France, which received $2.6 billion in financial support from the United States. The French defeat at the Dien Bien Phu was followed by a peace conference in Geneva. As a result of the conference, Laos, Cambodia, and Vietnam received their independence, and Vietnam was temporarily divided between an anti-Communist South and a Communist North. In 1956, South Vietnam, with American backing, refused to hold unification elections. By 1958, Communist-led guerrillas, known as the Viet Cong, had begun to battle the South Vietnamese government.
To support the South's government, the United States sent in 2,000 military advisors--a number that grew to 16,300 in 1963. The military condition deteriorated, and by 1963, South Vietnam had lost the fertile Mekong Delta to the Viet Cong. In 1965, President Lyndon Johnson escalated the war, commencing air strikes on North Vietnam and committing ground forces--which numbered 536,000 in 1968. The 1968 Tet Offensive by the North Vietnamese turned many Americans against the war.
The next president, Richard Nixon, advocated Vietnamization, withdrawing American troops and giving South Vietnam greater responsibility for fighting the war. In 1970, Nixon attempted to slow the flow of North Vietnamese soldiers and supplies into South Vietnam by sending American forces to destroy Communist supply bases in Cambodia. This act violated Cambodian neutrality and provoked antiwar protests on the nation's college campuses.
From 1968 to 1973, efforts were made to end the conflict through diplomacy. In January 1973, an agreement was reached; U.S. forces were withdrawn from Vietnam, and U.S. prisoners of war were released. In April 1975, South Vietnam surrendered to the North, and Vietnam was reunited.