Lon Nol was born on November 13, 1913 in Prey Veng Province, Cambodia.
Lon Nol entered civil service after completing his secondary school education in Saigon; he transferred to the army as a lieutenant to fight the Viet Minh after World War II. He became Cambodia defense minister in 1960, and the following year he attained the rank of Lieutenant General.
He held a variety of ministerial offices under Prince Norodom Sihanouk regime, including that of prime minister in 1966-1967.
Abandoning Prince Sihanouk's policy of neutrality in the Indochina War, Lon Nol staged a coup d'etat on March 18, 1970, which ousted Prince Sihanouk (Cambodia Head of State) from power; he established close ties with the United States and South Vietnam, permitting their forces to operate on Cambodian territory against Vietnamese communist and Vietcong. And on October 9, 1970 he proclaimed Cambodia as a republic, Khmer Republic, ending the country more than one thousand years-old monarchy, which was established with the ascending to the throne of King Jayavarman II in 802 A.D.
In 1971 Lon Nol acquired the rank of marshal. On March 10, 1972, Lon Nol assumed total power over the Khmer Republic by proclaiming himself as president, prime minister and defense minister; he was inaugurated as president of the republic on March 14, 1972.
On April 1, 1975, with Khmer Rouge Communist insurgents only a few miles from the capital, Lon Nol left the country; he came to Fullerton, California, U.S. and lived there until his death on November 17, 1985.