A military coup against President Ngô Đình Diệm of South Vietnam is crushed.

The president of the Socialist Republic of Vietnam is the head of state of Vietnam, elected by the National Assembly of Vietnam from its delegates. Since Vietnam is a one-party state, candidates for the post are nominated by the Central Committee of the Communist Party of Vietnam. The officeholder is generally considered to hold the second-highest position in the political system, practically after the general secretary of the Communist Party of Vietnam. As head of state, the president represents Vietnam both domestically and internationally, and maintains the regular and coordinated operation and stability of the national government and safeguards the independence and territorial integrity of the country.

Ngô Đình Diệm was a South Vietnamese politician who was the final prime minister of the State of Vietnam (1954–1955) and later the first president of South Vietnam from 1955 until his capture and assassination during the CIA-backed 1963 coup d'état.

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.