Between 1975 and 1979, one of the worst genocides of the 20th century unfolded in Cambodia. Under the rule of Pol Pot and the Khmer Rouge, an estimated 1.5 to 2.2 million Cambodians died from execution, starvation, forced labor, and disease. The roots of this catastrophe stretch back further than 1975, shaped by a decade of war, bombing, and political upheaval that tore the country apart before the Khmer Rouge ever took power.
In 1965, Prince Sihanouk officially severed Cambodia’s ties with the United States and declared the country neutral in the Vietnam War. That decision allowed North Vietnamese communist forces to use Cambodian territory as a military corridor. The U.S. responded with an extensive bombing campaign targeting both military sites and Cambodian villages. Between 1965 and 1969, American forces dropped more explosives on Cambodia than all Allied bombing combined during World War II. More than 150,000 people were killed, the vast majority of them civilians.
The bombing campaign had a direct political consequence. The Khmer Rouge, a small, radical communist movement operating from remote jungle and mountain regions, grew rapidly during this period. Widespread civilian casualties and government instability drove more Cambodians into the arms of the insurgency. The Khmer Rouge allied themselves with the deposed Prince Sihanouk, whose name still carried weight across the country, and used that association to build support in rural communities they had not previously reached.
On April 17, 1975, Khmer Rouge forces marched into Phnom Penh and seized control of the capital. The victory transferred power not to Sihanouk, but to Pol Pot, the Khmer Rouge’s ideological leader. Pol Pot was driven by a vision of an agrarian utopia — a classless, self-sufficient peasant society stripped of money, religion, and foreign influence. He looked to the rural ethnic communities of northeastern Cambodia as his model, people who farmed their own food and lived outside the cash economy. Everything connected to modern urban life was a target.
Within days of taking Phnom Penh, the Khmer Rouge began emptying the cities. Pol Pot renamed the country Kampuchea, abolished the national currency, closed the borders, and revoked all private property. Urban residents — regardless of age, profession, or health — were forced into the countryside to work on collective farms. Hospitals were abandoned. Schools were shut down. Cambodia was cut off entirely from the outside world.
The forced evacuation of Phnom Penh sent hundreds of thousands of people streaming into the streets. The sick were pulled from hospital beds. The elderly and wounded were made to walk alongside everyone else. Those who refused to comply, or who were too weak to move, were shot on the spot. The scenes from those first days captured the scale of what was coming.
As Phnom Penh fell, thousands of Cambodians rushed toward the French Embassy — one of the few places that offered any possibility of protection. Refugees climbed fences and pressed against the gates, desperate to get inside. The embassy was overwhelmed almost immediately.
Out in the streets, the chaos was visible everywhere. Injured civilians sheltered in hospitals that the Khmer Rouge would soon shut down. Others gathered in market areas or along roadsides with nowhere to go.
The Khmer Rouge recruited most of their soldiers from rural villages and ethnic minority groups who had long been looked down on by the urban elite and wealthy class. When the regime took power, those roles were violently reversed. Former soldiers and officers, teachers, doctors, lawyers, anyone who wore glasses or spoke a foreign language was labeled an intellectual and marked for death. The Khmer Rouge also accused many people of being foreign agents or spies working against the revolution. These accusations were almost always fabricated, and the accused had no avenue for appeal.
Among the most disturbing features of the Khmer Rouge army was its use of child soldiers. Boys who were barely teenagers carried rifles and enforced the regime’s orders. Some were photographed displaying machine guns. Others stood guard over prisoners or participated directly in killings. These children were recruited young, indoctrinated thoroughly, and given authority over adults.
The most notorious detention center under the Khmer Rouge was Tuol Sleng, also known as Security Prison 21, or S-21. It was a former high school in Phnom Penh converted into an interrogation and torture facility. Nearly 20,000 people were imprisoned there. Only seven survived. Every prisoner was photographed upon arrival — men, women, children, the elderly. Those photographs remain among the most haunting records of the genocide.
Entire families were brought to Tuol Sleng together. If a person was accused, their spouse, children, and parents were taken too. None were spared because of their age.
Torture at Tuol Sleng was systematic and documented. Guards used beatings with fists, sticks, and electric wire; burning with cigarettes; electric shocks; waterboarding; suffocation with plastic bags; jabbing with needles; ripping out fingernails; forcing prisoners to eat feces; and placing centipedes and scorpions on the bodies of the detained. The goal was to extract confessions — confessions that were almost entirely forced fabrications used to justify further arrests and executions.
After prisoners at Tuol Sleng were killed, their bodies were transported to execution sites outside the city. The largest of these was Choeung Ek, located a few kilometers south of Phnom Penh. It became the primary mass grave for victims processed through S-21. As the regime’s economy collapsed and international sanctions tightened, bullets became scarce. Executioners were ordered to use pick axes, iron bars, and other makeshift weapons to carry out killings rather than waste ammunition.
Violence was not confined to prisons and designated execution sites. Khmer Rouge soldiers killed civilians openly in the streets and in villages across the country. Public executions were used to demonstrate power and suppress any resistance. Bodies were left where they fell.
On the collective farms, survival depended entirely on the Khmer Rouge’s decisions about food distribution. The government deliberately reduced rations to control the population and redirected agricultural output to fund the regime. People died in enormous numbers from starvation, exhaustion, and preventable illness. Medical care was essentially nonexistent. Those who became too sick or too weak to work were executed rather than treated.
Those who managed to flee the country faced their own ordeal. Cambodians crossed into Thailand in waves, many of them severely malnourished, injured, or sick. Thai border patrols encountered some of the most extreme cases — including children killed by Khmer Rouge soldiers before they could reach safety.
In January 1979, Vietnamese forces invaded Cambodia and dismantled the Khmer Rouge government in a matter of weeks. Pol Pot and his forces retreated to the remote northeastern jungles, where the movement continued as an armed insurgency for years. Pol Pot himself lived in that region until 1997, when he died under house arrest. He was never tried for his crimes. None of the senior members of his regime faced a court of law while the regime was still in living memory for millions of survivors.
