Four year after their victory against the USA, Vietnam turned its military attentions to Cambodia, where they captured the capital of Phnom Penh on this day in 1979. In doing so, they toppled the short-lived but incredibly brutal Khmer Rouge revolutionary regime led by the psychotic Saloth Sar, better known by the pseudonym Pol Pot.
Born into wealth, Pot was educated in France, but spent most of his time reading communist manifestos rather than studying his chosen field of radio electronics. He flunked out and returned home, where he hooked up with Cambodia's home-grown commies. Rising through the revolutionary ranks, he eventually became enough of a pain-in-the-ass that the American-backed Sihanouk royal family chased him into the mountains. There, he drew inspiration from the local tribesmen, whom he considered to be the modern equivalent of Cambodia's original Khmer civilization.
In 1970, President Richard Nixon withdrew support for Sihanouk, installing the right-wing military dictatorship of General Lon Nol. Nol's troops fought both the Vietnamese troops who used Cambodia as a refuge from American forces, and Pot's Khmer army. Around the same time, Nixon illegally ordered a secret, massive bombing campaign against Cambodia, killing hundreds of thousands and driving the nation towards starvation and madness.
As Cambodia burned, Pol Pot's anti-Western vision started looking good to a lot of people. When the U.S. withdrew from Southeast Asia, the Khmer Rouge - aided by thousands of true-believing Vietnamese troops who now had nothing better to do - rushed in to fill the void. Depending on your political point of view, decades spent in the mountains under constant attack had either driven Pot insane or sharpened his revolutionary resolve. Determined that his new Kampuchean People's Republic would be a purely agrarian, self-sufficient society, free from capitalism, Pot shut down all schools and factories, abolished currency, forbid the use of technology, and eliminated property rights.
To prevent ideological pollution from complicating (and thus corrupting) his movement, Pot targeted intellectuals - which meant everyone from university professors to people who could speak a foreign language - and the cities, which Pot and his jungle-dwelling army despised above all else. A mass evacuation of all cities immediately ordered. Between 1975 and 1978, more than two million people died in what has come to be known as the Killing Fields, where Cambodia's despised city-dwellers were either murdered for fun or forced to work until they dropped dead. Millions more toiled for years until the neighboring Vietnamese regime learned of the insanity going on and invaded, sending Pot and his Khmer Rouge army running back to the hills.
Much to the relief of surviving Cambodians, the Vietnamese established a moderate communist government and provided protection from the Khmer Rouge, who were now waging a low-intensity guerrilla war against the communist forces with whom they had once been aligned. It was at this point that the American government finally began supporting Pol Pot and his plucky band of anti-communist mountain rebels.