Cambodia's long period of bouncing back and forth between Thai and Vietnamese masters ended in 1864, when French gunboats intimidated King Norodom I (r 1860-1904) into signing a treaty of protectorate. French control of Cambodia, which developed as a sideshow to French-colonial interests in Vietnam, initially involved little direct interference in Cambo­dia's affairs. More importantly, the French presence prevented Cambodia's expansionist neighbours from annexing any more Khmer territory and helped keep Norodom on the throne despite the ambitions of his rebel­lious half-brothers.

By the 1870s French officials in Cambodia began pressing for greater control over internal affairs. In 1884, Norodom was forced into signing a treaty that turned his country into a virtual colony. This sparked a two-year rebellion that constituted the only major anti-French movement in Cambodia until after WWII. This uprising ended when the king was persuaded to call upon the rebel fighters to lay down their weapons in exchange for a return to the pretreaty arrangement.

During the next two decades senior Cambodian officials, who saw cer­tain advantages in acquiescing to French power, opened the door to direct French control over the day-to-day administration of the country. At the same time the French maintained Norodom's court in a splendour unseen since the heyday of Angkor, thereby greatly enhancing the symbolic posi­tion of the monarchy. The French were able to pressure Thailand into re­turning the northwest provinces of Battambang, Siem Reap and Sisophon in 1907, in return for concessions of Lao territory to the Thais, returning Angkor to Cambodian control for the first time in more than a century.

King Norodom I was succeeded by King Sisowath (r 1904-27), who was succeeded by King Monivong (r 1927-41). Upon King Monivong's death, the French governor general of Japanese-occupied Indochina, Admiral Jean Decoux, placed 19-year-old Prince Norodom Sihanouk on the Cam­bodian throne. Sihanouk would prove pliable, so the assumption went, but this proved to be a major miscalculation (see the boxed text, opposite).

During WWII, Japanese forces occupied much of Asia, and Cambodia was no exception. However, with many in France collaborating with the occupying Germans, the Japanese were happy to let these French allies control affairs in Cambodia. The price was conceding to Thailand (a Japanese ally of sorts) much of Battambang and Siem Reap Provinces once again, areas that weren't returned until 1947. However, with the fall of Paris in 1944 and French policy in disarray, the Japanese were forced to take direct control of the territory by early 1945. After WWII, the French returned, making Cambodia an autonomous state within the French Union, but retaining de facto control. The French deserved independence it seemed, but not its colonies. The immediate postwar years were marked by strife among the country's various political factions, a situation made more unstable by the Franco-Viet Minh War then raging in Vietnam and Laos, which spilled over into Cambodia. The Vietnamese, as they were also to do 20 years later in the war against Lon Nol and the Americans, trained and fought with .bands of Khmer Issarak (Free Khmer) against the French authorities.