The Republic of Vietnam (RVN; Vietnamese: Việt Nam Cộng hòa, VNCH), commonly known as South Vietnam, was a country in Southeast Asia that existed from 1955 to 1975. It first garnered 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. Although South Vietnam failed to gain admission into the United Nations as a result of a Soviet veto in 1957, its sovereignty was recognized by 95 countries as of January 1975. It was succeeded by the communist-controlled Republic of South Vietnam in 1975. In 1976, North Vietnam and the Republic of South Vietnam merged to form the Socialist Republic of Vietnam.
The aftermath of World War II saw the communist-led Viet Minh, under Ho Chi Minh, seize power and proclaim the Democratic Republic of Vietnam (DRV) in Hanoi in September 1945, initiating civil conflicts. In 1949, during the First Indochina War, the French and Vietnamese nationalists established the State of Vietnam (SVN), led by former emperor Bảo Đại, as an anti-communist alternative. Returning from exile in June 1954, Ngô Đình Diệm, recognized as the prominent anti-communist and anti-colonialist figure, was appointed prime minister of the SVN.
After the 1954 Geneva Conference, the DRV took control of North Vietnam, while the SVN administered South Vietnam, which encompassed the southern and part of the central regions of the country. A 1955 referendum on the state's future form of government was widely marred by electoral fraud and resulted in the deposal of Bảo Đại by Prime Minister Ngô Đình Diệm, who proclaimed himself president of the new republic on 26 October 1955. Diệm adopted personalism, a doctrine rejecting communism, liberalism and capitalism, as the official ideology of the regime. His authoritarian tendencies provoked resentment and opposition during the communist insurgency, and Diệm was killed in a CIA-backed military coup led by general Dương Văn Minh in 1963, and a series of short-lived military governments followed which ended in 1967 with General Nguyễn Cao Kỳ ratifying a constitution which formally granted liberal democratic freedoms. General Nguyễn Văn Thiệu then led the country after a disputed civilian presidential election from 1967 until 1975. Amidst escalating communist aggression, his rule grew authoritarian while maintaining a degree of political freedoms and an active civil society.
The Vietnam War emerged from an insurgency by the newly organized Viet Cong, armed and supported by North Vietnam, with backing mainly from China and the Soviet Union. Larger escalation of the insurgency occurred in 1965 with American intervention and the introduction of regular forces of Marines, followed by Army units to supplement the cadre of military advisors guiding the Republic's armed forces. A regular bombing campaign over North Vietnam was conducted by offshore US Navy airplanes, warships, and aircraft carriers joined by Air Force squadrons through 1966 and 1967. Fighting peaked up to that point during the Tet Offensive of February 1968, when there were over a million South Vietnamese soldiers, 500,000 U.S. soldiers, and 100,000 soldiers from other allied nations such as South Korea, Australia, and Thailand in South Vietnam. What started as a guerrilla war eventually turned into a more conventional fight as the balance of power became equalized. An even larger, armored invasion from the North commenced during the Easter Offensive following US ground-forces withdrawal, and had nearly overrun some major southern cities until being beaten back.
Despite a truce agreement under the Paris Peace Accords, concluded in January 1973 after five years of on-and-off negotiations, fighting continued almost immediately afterwards. The regular North Vietnamese army and Viet Cong auxiliaries launched a major combined-arms conventional invasion in 1975. Communist forces overran Saigon on 30 April 1975 in what is called the fall of Saigon, marking the end of the Republic of Vietnam. On 2 July 1976, the Democratic Republic of Vietnam (North Vietnam) and the North Vietnamese-controlled Republic of South Vietnam merged to form the Socialist Republic of Vietnam; Saigon was renamed Ho Chi Minh City.
The official name of the South Vietnamese state was the Republic of Vietnam (Vietnamese: Việt Nam Cộng hòa). The North was officially known as the Democratic Republic of Vietnam. Việt Nam (Vietnamese pronunciation: [viət naːm]) was the name adopted by Emperor Gia Long in 1804. It is a variation of "Nam Việt" (南越, 'Southern Yue'), a name used in ancient times. In 1839, Emperor Minh Mạng renamed the country Đại Nam ("Great South"). In 1945, the nation's official name was changed back to "Vietnam". The name is also sometimes rendered as "Viet Nam" in English.
Before 1954, the three regions of Vietnam were often translated into English as North, Central, and South Viet-Nam. Following the 1954 partition of Vietnam into communist and anti-communist parts, it was recommended to refer to Vietnam south of the 17th parallel as Southern Vietnam, but later on, South Vietnam became common usage. Other names commonly used during its existence include Free Vietnam, the national government, and the Government of Viet Nam (GVN).
Republican ideas entered French Indochina in the early 20th century, introducing new concepts about the modern nation-state, initially transmitted via China and Japan. By the 1920s, these ideas were embraced by Vietnamese elites, including both revolutionaries and reformers. They influenced Vietnamese independence movements, though suppressed by French colonial authorities. Republican activists were far more popular than communists in the competition between the two groups for leadership of the nationalist movement. This schism long predated the global Cold War and US intervention. Drawing from the deep-rooted tradition of republicanism, South Vietnamese political forces, despite their government's dependence on American assistance, pursued their nation-building projects while vehemently resisting foreign interference.
Caught between communism and colonial reconquest
During World War II, Indochina was administered by Vichy France and occupied by Japan in September 1940. Following the ousting of the French in March 1945 and the surrender of Japan in August of the same year, the Vietnamese were locked in a civil strife over the destiny of their post-colonial state. The nationalist sentiment that had intensified during World War II prepared the ground for the communist-led Viet Minh, which, cloaked in nationalism, seized power from the collapsing Empire of Vietnam during the August Revolution and proclaimed the Democratic Republic of Vietnam (DRV) in Hanoi. In the meantime, the 16th parallel was established following the Potsdam Conference, dividing Vietnam into two military zones: Chinese Nationalist forces occupied the North and British forces the South to disarm Japanese troops. In the South, British-led forces facilitated the return of the French, who fought multiple Vietnamese groups and secured control over Saigon and other urban centers.
The Viet Minh sought to consolidate power by terrorizing and purging rival Vietnamese nationalist groups and Trotskyist activists. In 1946, the Franco-Chinese and Ho–Sainteny Agreements enabled French forces to replace the Chinese north of the 16th parallel and facilitated a coexistence between the DRV and the French that strengthened the Viet Minh while undermining the nationalists. That summer, the Viet Minh colluded with French forces to eliminate nationalists, targeted for their ardent anti-colonialism. By eliminating the nationalist parties, the Viet Minh had undermined Vietnam's broader ability to resist French reconquest. The First Indochina War began on 19 December 1946, as French forces reasserted control over Hanoi and other cities. A number of anti-colonialist and anti-communist nationalists, caught between the two sides of the war, chose an uneasy neutrality and were at times labeled as attentistes, including Ngô Đình Diệm and certain Đại Việt politicians. With the internationalization of the war in 1950, many of these figures ultimately stepped off the fence and entered the political fray.