Colonel Phạm Ngọc Thảo of the Army of the Republic of Vietnam, along with Generals Lâm Văn Phát and Trần Thiện Khiêm attempted a coup against the military junta of Nguyễn Khánh.

Phạm Ngọc Thảo, also known as Albert Thảo, was a Vietnamese military officer and spy. He was a communist sleeper agent of the Việt Minh who infiltrated the Army of the Republic of Vietnam (ARVN) and also became a major provincial leader in South Vietnam. In 1962, he was made overseer of Ngô Đình Nhu's Strategic Hamlet Program in South Vietnam and deliberately forced it forward at an unsustainable speed, causing the production of poorly equipped and poorly defended villages and the growth of rural resentment toward the regime of President Ngô Đình Diệm, Nhu's elder brother. In light of the failed land reform efforts in North Vietnam, the Hanoi government welcomed Thao's efforts to undermine Diem.

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 on 30 April 1975. Its predecessor was the ground forces of the Vietnamese National Army, established on 8 December 1950, representing Vietnam to fight in the First Indochina War against the communist Viet Minh rebels. 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.

Lâm Văn Phát was a Major general in the South Vietnamese Army of the Republic of Vietnam (ARVN). He is best known for leading two coup attempts against General Nguyễn Khánh in September 1964 and February 1965. Although both failed to result in his taking power, the latter caused enough instability that it forced Khánh to resign and go into exile.

Trần Thiện Khiêm was a South Vietnamese soldier and politician, who served as a General in the Army of the Republic of Vietnam (ARVN) during the Vietnam War. He was born in Saigon, Cochinchina, French Indochina. During the 1960s, he was involved in several coups. He helped President Ngô Đình Diệm put down a November 1960 coup attempt and was rewarded with a promotion. In 1963, however, he was involved in the coup that deposed and assassinated Diêm.