At the onset of this terrible decade in Cambodian history, the Communist Party of Kampuchea's (CPK) armed opposition to prince Norodom Sihanouk was gaining momentum. Those who would be remembered as the “Khmers Rouges,” a term coined by Sihanouk himself, occupied bases in the northeast and northwest corners of the country from which they rendered unsafe as much as a fifth of Cambodia's territory (Chandler, 1996). To the west, Vietnamese communist troops held bases on Cambodian soil. Up to this point, the population of Cambodia can be reasonably well extrapolated from the demographic analysis of its 1962 census (Migozzi, 1973; Siampos, 1970).
In March 1970, the National Assembly voted Sihanouk out of power to the benefit of his own Prime Minister, Lon Nol. Sihanouk learned of the coup while on holiday, out of the country. With the support of North Vietnam, he took command of an opposition alliance whose military force on the ground consisted mostly of his former foes of the CPK. In part because of the North Vietnamese support to the opposition, the new Cambodian government started a strong campaign against the half million ethnic Vietnamese then living in Cambodia and suspected of supporting Sihanouk. The Cambodian army killed thousands of Vietnamese civilians (Chandler, 1996:205), and about 300,000 people are believed to have fled—or to have been expelled by force—to Vietnam during the first eight months of 1970 (Migozzi, 1973:44). But the inexperienced and ill-equipped army failed to drive North Vietnamese forces out of the country.
Over the next four years, the Lon Nol government gradually lost control over the Cambodian countryside. The mortality impact of the civil war is difficult to assess, but the main controversy in this respect concerns the impact of a massive bombardment of eastern Cambodia by U.S. planes in early 1973—sometimes referred to as the “Kissinger war” because of former U.S. Secretary of State Henry Kissinger's involvement— meant to weaken the North Vietnamese troops. Sihanouk (1986:144) mentions a widely circulated but unsubstantiated estimate that 700,000 Cambodians were killed under the Lon Nol government. Kiernan (1989) argues that the impact of the U.S. bombing could not be more than 150,000 deaths, and subsequent reevaluations of the demographic data situated
Although more emphasis is given here to deaths and refugees movements, the historical account in this section borrows liberally from Chandler (1996), to which the reader is referred for more details about the political developments of the decade. For an unforgettable, personal account of the post-1975 period, see Ung (2000). For a discussion of the available demographic data, see Huguet (1992), Banister and Johnson (1993), and Heuveline (1998a).