South Vietnam, officially the Republic of Vietnam (Vietnamese: Việt Nam Cộng Hòa), was a state governing the southern half of Vietnam from 1955 to 1975. It received international recognition in 1949 as the "State of Vietnam" (1949–55), and later as the "Republic of Vietnam" (1955–75). Its capital was Saigon. The term "South Vietnam" became common usage in 1954, when the Geneva Conference provisionally partitioned Vietnam into communist and non-communist parts.
South Vietnam's origins can be traced to the French colony of Cochinchina, which consisted of the southern third of Vietnam and was a subdivision of French Indochina. After World War II, the Viet Minh, led by Ho Chi Minh, proclaimed the establishment of a Democratic Republic of Vietnam in Hanoi in September, 1945. In 1949, anti-communist Vietnamese politicians formed a rival government in Saigon led by former emperor Bảo Đại. Bảo Đại was deposed by Prime Minister Ngô Đình Diệm in 1955, who proclaimed himself president after a referendum. After Diệm was killed in a military coup led by general Dương Văn Minh in 1963, there was a series of short-lived military governments. General Nguyễn Văn Thiệu led the country from 1967 until 1975. The Vietnam War began in 1959 with an uprising by Viet Cong forces armed and controlled by Democratic Republic of Vietnam. Fighting climaxed during the Tet Offensive of 1968, when there were over 1.5 million South Vietnamese soldiers and 500,000 U.S. soldiers in South Vietnam. Despite a peace treaty concluded in January 1973, fighting continued until the North Vietnamese and Viet Cong armies overran Saigon on 30 April 1975, marking the end of the South Vietnamese state.