French colonial period (1863–1953)[edit]

Main articles: French Protectorate of Cambodia and French Indochina

Norodom of Cambodia

French Indochina in 1913.

In 1863, King Norodom signed an agreement with the French to establish a protectorate over his kingdom. The state gradually came under French colonial rule.^[115]

During World War II, the 1940–41 Franco-Thai War left the French Indochinese colonial authorities in a position of weakness. The Vichy government signed an agreement with Japan to allow the Japanese military transit through French Indochina.^[116]

Meanwhile the Thai government, under the pro-Japanese leadership of Field Marshal Plaek Phibunsongkhram, took advantage of its position and invaded Cambodia's western provinces.^[117]

Cambodia's situation at the end of the war was chaotic. The Free French, under General Charles de Gaulle, were determined to recover Indochina, though they offered Cambodia and the other Indochinese protectorates a carefully circumscribed measure of self-government. Convinced that they had a "civilizing mission", they envisioned Indochina's participation in a French Union of former colonies that shared the common experience of French culture.