Pol Pot

=== Collectivisation and the conquest of Phnom Penh: 1973–1975 ===
In May 1973, Pol Pot ordered the collectivisation of villages in territory that the Khmer Rouge controlled.{{sfnm|1a1=Chandler|1y=1992|1p=105|2a1=Short|2y=2004|2pp=246–47}} This move was both ideological, in that it built a socialist society void of private property, and tactical, in that it allowed the Khmer Rouge greater control over the food supply, ensuring that farmers did not provision government forces.{{sfn|Short|2004|p=247}} Many villagers resented the collectivisation and slaughtered their livestock to prevent it from becoming collective property.{{sfn|Short|2004|p=246}} Over the following six months, about 60,000 Cambodians fled from areas under Khmer Rouge control.{{sfn|Short|2004|p=247}} The Khmer Rouge introduced [[conscription]] to bolster its forces.{{sfn|Short|2004|p=249}} Relations between the Khmer Rouge and the North Vietnamese remained strained. After the latter temporarily reduced the flow of arms to the Khmer Rouge, in July 1973 the CPK Central Committee agreed that the North Vietnamese should be considered "a friend with a conflict".{{sfn|Short|2004|pp=249–51}} Pol Pot ordered the internment of many of the Khmer Rouge who had spent time in North Vietnam and were considered too sympathetic to them. Most of these people were later executed.{{sfn|Short|2004|pp=249–50}}

In summer 1973, the Khmer Rouge launched its first major assault on Phnom Penh, but was forced back amid heavy losses.{{sfnm|1a1=Chandler|1y=1992|1p=104|2a1=Short|2y=2004|2p=249}} Later that year, it began bombarding the city with artillery.{{sfnm|1a1=Chandler|1y=1992|1p=107|2a1=Short|2y=2004|2p=254}} In the autumn, Pol Pot traveled to a base at Chrok Sdêch on the eastern foothills of the [[Cardamom Mountains]].{{sfn|Short|2004|p=251}} By winter, he was back at the Chinit Riber base where he conferred with Sary and Chea.{{sfn|Short|2004|p=255}} He concluded that the Khmer Rouge should start talking openly about its commitment to making Cambodia a socialist society and launch a secret campaign to oppose Sihanouk's influence.{{sfn|Short|2004|p=256}} In September 1974, a Central Committee meeting was held at Meakk in Prek Kok commune.{{sfn|Short|2004|p=256}} There the Khmer Rouge agreed that it would expel the populations of Cambodia's cities to rural villages. They thought this was necessary to dismantle capitalism which they associated with the urban culture.{{sfnm|1a1=Chandler|1y=1992|1p=107|2a1=Short|2y=2004|2pp=256–57}}

[[File:View of Phnom Penh from CH-53.jpg|thumb|left|View of Phnom Penh from a US helicopter, 12 April 1975]]

By 1974, Lon Nol's government had lost a great deal of support, both domestically and internationally.{{sfn|Short|2004|p=261}} In 1975, the troops defending Phnom Penh began discussing surrender, eventually doing so and allowing the Khmer Rouge to enter the city on 17 April.{{sfnm|1a1=Chandler|1y=1992|1p=108|2a1=Short|2y=2004|2pp=265–68}} There, Khmer Rouge soldiers executed between 700 and 800 senior government, military, and police figures.{{sfn|Short|2004|p=271}} Other senior figures escaped; Lon Nol fled into exile in the US.{{sfnm|1a1=Chandler|1y=1992|1p=107|2a1=Short|2y=2004|2p=263}} He left [[Saukham Khoy]] as acting president, although he too fled aboard a departing US Navy ship just twelve days later.{{sfn|Short|2004|p=264}} Within the city, Khmer Rouge militia under the control of different Zone commanders clashed with one another, partly as a result of [[wikt:turf war|turf war]]s and partly due to the difficulty of establishing who was a group member and who was not.{{sfn|Short|2004|p=275}}

The Khmer Rouge had long viewed Phnom Penh's population with mistrust, particularly as the city's numbers had been swelled by peasant refugees who had fled the Khmer Rouge's advance and were considered to be traitors.{{sfnm|1a1=Chandler|1y=1992|1p=108|2a1=Short|2y=2004|2p=254}} Shortly after taking the city, the Khmer Rouge announced that its inhabitants had to evacuate to escape a forthcoming US bombing raid; the group falsely claimed that the population would be allowed to return after three days.{{sfnm|1a1=Chandler|1y=1992|1p=108|2a1=Short|2y=2004|2p=271}} This evacuation entailed moving over 2.5 million people out of the city with very little preparation;{{sfn|Short|2004|p=272}} between 15,000 and 20,000 of these were removed from the city's hospitals and forced to march.{{sfn|Short|2004|p=273}} Checkpoints were erected along the roads out of the city where Khmer Rouge cadres searched marchers and removed many of their belongings.{{sfn|Short|2004|pp=278–79}} The march took place in the hottest month of the year and an estimated 20,000 people died along the route.{{sfnm|1a1=Chandler|1y=1992|1pp=108–09|2a1=Short|2y=2004|2pp=272–73}}{{sfn|Short|2004|p=275}} For the Khmer Rouge, emptying Phnom Penh was considered as demolishing not just capitalism in Cambodia, but also Sihanouk's power base and the spy network of the U.S. [[Central Intelligence Agency]] (CIA). This dismantling facilitated Khmer Rouge dominance over the country and enabled driving the urban population toward agricultural production.{{sfn|Short|2004|p=287}}