The Army of the Republic of Vietnam (ARVN; Vietnamese: Lục quân Việt Nam Cộng hòa), also known as the South Vietnamese army (SVA), were the ground forces of the South Vietnamese military from its inception in 1955 until the Fall of Saigon in 1975. It is estimated to have suffered 1,394,000 casualties (killed and wounded) during the Vietnam War.
The ARVN begun as a post-colonial army trained and closely affiliated with the US and had engaged in conflict since its inception. Several dramatic changes occurred throughout its lifetime, initially from a 'blocking-force' to more modern a conventional force using helicopter deployment in combat. During the U.S-intervention the role of the ARVN was marginalised to a defensive role with an incomplete modernisation, and transformed again most notably following Vietnamization as it was up-geared, expanded and reconstructed to fulfil the role of the departing US Forces. By 1974 it had became much more effective with foremost counterinsurgency expert and Nixon adviser Robert Thompson noting that Regular Forces were very well-trained and second only to US and IDF forces in the free-world and with General Creighton Abrams remarking that 70% of units were on par with the US Army. However, the rushed retreat of American forces through Vietnamization meant the armed forces could not effectively fulfil all the aims of the program and had became completely dependent on US equipment, given it was meant to fulfil the departing role of the United States.
At its peak, an estimated 1 in 9 citizen of South Vietnam were enlisted and it had became the fourth-largest army in the world composed of Regular Forces and more voluntary Regional Militias and Village-level militias.
Unique in serving a dual military-civilian administrative purpose in direct competition with the Viet Cong political and armed wing, the PLAF. The ARVN had in addition became a component of political power and notably suffered from continual issues of political loyalty appointments, corruption in leadership, factional in-fighting and occasional open conflict between itself .
After the fall of Saigon to the North Vietnamese army (NVA), the ARVN was dissolved. While some high-ranking officers had fled the country to the United States or elsewhere, thousands of former ARVN officers were sent to reeducation camps by the communist government of the new, unified Socialist Republic of Vietnam.
On March 8, 1949, after the Élysée Accords the State of Vietnam was recognized by France as an independent country ruled by the Vietnamese Emperor Bảo Đại, and the Vietnamese National Army (VNA) was soon created. The VNA fought in joint operations with the French Union's French Far East Expeditionary Corps against the Viet Minh forces led by Ho Chi Minh. The VNA fought in a wide range of campaigns including but not limited to the Battle of Nà Sản (1952), Operation Atlas (1953) and the Battle of Dien Bien Phu (1954).
Benefiting from French assistance, the VNA quickly became a modern army modelled after the Expeditionary Corps. It included infantry, artillery, signals, armored cavalry, airborne, airforce, navy and a national military academy. By 1953 troopers as well as officers were all Vietnamese, the latter having been trained in Ecoles des Cadres such as Da Lat, including Chief of Staff General Nguyễn Văn Hinh who was a French Union airforce veteran.