In late-1952 King Sihanouk dissolved the fledgling parliament, declared martial law and embarked on his 'royal crusade': his travelling campaign to drum up international support for his country's independence.

Independence was proclaimed on 9 November 1953 and recognised by the Geneva Conference of May 1954, which ended French control of Indochina. In 1955, Sihanouk abdicated, afraid of being marginalized amid the pomp of royal ceremony. The 'royal crusader' became 'citizen Sihanouk'. He vowed never again to return to the throne. Meanwhile his father became king. It was a masterstroke that offered Sihanouk both royal authority and supreme political power. His newly established party, Sangkum Reastr Niyum (People's Socialist Community Party), won every seat in parliament in the September 1955 elections and Sihanouk was to dominate Cambodian politics for the next 15 years. Although he feared the Vietnamese communists, Sihanouk considered South Vietnam and Thailand, both allies of the USA (which he mis­trusted), the greatest threats to Cambodia's security, even survival. In an attempt to fend off these many dangers, he declared Cambodia neutral in international affairs and refused to accept any further US aid, which had accounted for a substantial chunk of the country's military budget. He also nationalised many industries, including the rice trade. In May 1965 Sihanouk, convinced that the USA had been plotting against him and his family, broke diplomatic relations with Washington and tilted towards the North Vietnamese and China. In addition, he agreed to let the communists use Cambodian territory in their battle against South Vietnam and the USA.

These moves and his socialist economic policies alienated right-leaning elements in Cambodian society, including the army brass and the urban elite. At the same time, left-wing Cambodians, many of them educated abroad, deeply resented his internal policies, which did not allow for political dissent. Compounding Sihanouk's problems was the fact that all classes were fed up with the pervasive corruption in government ranks, some of it uncomfortably close to the royal family. Although most peasants revered Sihanouk as a semidivine figure, in 1967 a rural-based rebellion broke out in Samlot, Battambang, leading him to conclude that the greatest threat to his regime came from the left. Bowing to pressure from the army, he implemented a policy of harsh repression against left-wingers.

By 1969 the conflict between the army and leftist rebels had become more serious, as the Vietnamese sought sanctuary deeper in Cambodia. Sihanouk's political position had also greatly deteriorated - due in no small part to his obsession with film-making, which was leading him to neglect affairs of state. In March 1970, while Sihanouk was on a trip to France, General Lon Nol and Prince Sisowath Sirik Matak, Sihanouk's cousin, deposed him as chief of state, apparently with tacit US consent. Sihanouk took up residence in Beijing, where he set up a government-in-exile nominally in control of an indigenous Cambodian revolution­ary movement that Sihanouk had nicknamed the Khmer Rouge. This was a definitive moment in contemporary Cambodian history, as the Khmer Rouge exploited its partnership with Sihanouk to draw new re­cruits into their small organisation. Many former Khmer Rouge fighters argue that they 'went to the hills' (a euphemism for joining the Khmer Rouge) to fight for their king and knew nothing of Mao or Marxism.