In 1966, General Lon Nol was elected as prime minister of Cambodia, initially seen as an ally of Prince Norodom Sihanouk. However, rising unrest among military personnel frustrated by inadequate supplies and equipment, along with discontent from the middle class over the prince’s economic strategies, prompted Nol to reassess his position. By 1970, while Sihanouk was abroad, Lon Nol orchestrated a coup that ousted the prince from power, dissolved the monarchy, and rebranded the nation as the Khmer Republic.

From Beijing, Sihanouk issued a heartfelt plea urging his supporters to rise against Lon Nol. However, under Chinese influence, he ultimately decided to collaborate with the communists he had exiled in 1963 to form an alternative government. This alliance emerged as a significant turning point in Cambodian politics.

Meanwhile, details of Sihanouk’s secret agreement with North Vietnam emerged, igniting a national effort to eliminate the communist supply routes operating through Cambodian territory. Thousands of Cambodians enlisted in the military to address this threat; however, they faced significant challenges due to poor training and inadequate equipment, even with renewed financial backing from the US, which only exacerbated corruption.

The Cambodian forces struggled to contend with the seasoned Vietnamese fighters, resulting in the loss of tens of thousands of lives in combat. In 1971, Lon Nol was compelled to cease military operations against the North Vietnamese. The Khmer Rouge, led by Pol Pot, continued their advance toward Phnom Penh, controlling approximately 20% of Cambodia by 1970, predominantly in the northeast and northwest regions. By late 1972, they had captured nearly all areas except for Phnom Penh and a few provincial capitals. Although intense US bombing temporarily stalled their progress in 1973, the Khmer Rouge resumed their offensive.

By early 1975, Phnom Penh was encircled, cutting off access to the rest of the country. The US began airlifting supplies to the besieged city, but rampant corruption and ongoing conflict had severely impacted the population’s morale. When the Khmer Rouge entered Phnom Penh on April 17, 1975, they were met with a sense of relief from the weary citizens. Just two weeks later, on April 30, the last American troops departed from Saigon, coinciding with the advance of North Vietnamese forces, marking the conclusion of US military involvement in Indochina.

The four years of conflict resulted in the deaths of over 300,000 Cambodians due to fighting against both the Vietnamese and the Khmer Rouge, compounded by indiscriminate US bombing. While Sihanouk’s worst fears had come to fruition, the true horrors of Cambodia’s future were still to unfold.