Vietnam War: U.S. president Richard Nixon makes an unscheduled visit to South Vietnam and meets with President Nguyễn Văn Thiệu and U.S. military commanders.

The Vietnam War was an armed conflict in Vietnam, Laos, and Cambodia fought between North Vietnam and South Vietnam and their allies. North Vietnam was supported by the Soviet Union and China, while South Vietnam was supported by the United States and other anti-communist nations. The conflict was the second of the Indochina wars and a proxy war of the Cold War between the Soviet Union and US. The Vietnam War was one of the postcolonial wars of national liberation, a theater in the Cold War, and a civil war, with civil warfare a defining feature from the outset. Direct US military involvement escalated from 1965 until its withdrawal in 1973. The fighting spilled into the Laotian and Cambodian Civil Wars, which ended with all three countries becoming communist in 1975.

Richard Milhous Nixon was the 37th president of the United States, serving from 1969 until his resignation in 1974. A member of the Republican Party, he represented California in both houses of the United States Congress before serving as the 36th vice president under President Dwight D. Eisenhower from 1953 to 1961. His presidency saw the reduction of U.S. involvement in the Vietnam War, détente with the Soviet Union and China, the Apollo 11 Moon landing, and the establishment of the Environmental Protection Agency and Occupational Safety and Health Administration. Nixon's second term ended early when he became the only U.S. president to resign from office, as a result of the Watergate scandal.

South Vietnam, officially the Republic of Vietnam, was a country in Southeast Asia that existed from 1955 to 1975. It first garnered international recognition in 1949 as the associated State of Vietnam within the French Union, with its capital at Saigon. Since 1950, it was a member of the Western Bloc during the Cold War. Following the 1954 partition of Vietnam, it became known as South Vietnam and was established as a republic in 1955. South Vietnam was bordered by North Vietnam to the north, Laos to the northwest, Cambodia to the southwest, and Thailand across the Gulf of Thailand to the southwest. Its sovereignty was recognized by the United States and 87 other nations, though it failed to gain admission into the United Nations as a result of a Soviet veto in 1957. It was succeeded by the Republic of South Vietnam in 1975. In 1976, the Republic of South Vietnam and North Vietnam merged to form the Socialist Republic of Vietnam.