Nguyễn Chánh Thi was an officer in the Army of the Republic of Vietnam (ARVN). He is best known for being involved in frequent coups in the 1960s and wielding substantial influence as a key member of various juntas that ruled South Vietnam from 1964 until 1966, when he was overpowered by Republic of Vietnam Air Force chief and Prime Minister Nguyễn Cao Kỳ in a power struggle and exiled to the United States. Known for his flamboyant style and hostility to US advice, Thi's ouster was supported by the American leadership, who backed Kỳ's pro-US regime.

The Army of the Republic of Vietnam composed the ground forces of the South Vietnamese military from its inception in 1955 to the Fall of Saigon in April 1975. At the ARVN's peak, an estimated 1 in 9 citizens of South Vietnam were enlisted, composed of Regular Forces and the more voluntary Regional Forces and the Popular Force militias. It is estimated to have suffered 1,394,000 casualties during the Vietnam War.