| Native Name: | |
| Conventional Long Name: | Kingdom of Kampuchea |
| Common Name: | Kampuchea |
| Era: | World War II |
| Status: | Puppet state of the Empire of Japan (until 15 August 1945) |
| Event Pre: | Coup d'état |
| Date Pre: | 9 March 1945 |
| Event Start: | Puppet state established |
| Date Start: | 13 March |
| Year Start: | 1945 |
| Event End: | French rule restored |
| Date End: | 16 October |
| Year End: | 1945 |
| Life Span: | 1945 |
| Event1: | Japanese surrender |
| Date Event1: | 15 August 1945 |
| Flag P1: | Flag of Cambodia under French protection.svg |
| P1: | French protectorate of CambodiaFrench Cambodia |
| Flag S1: | Flag of Cambodia under French protection.svg |
| S1: | French protectorate of CambodiaFrench Cambodia |
| Flag: | Flag of Cambodia |
| Symbol: | Coat of arms of Cambodia |
| National Anthem: | Central Khmer: នគររាជ "Majestic Kingdom" |
| Capital: | Phnom Penh |
| Government Type: | Absolute monarchy under Japanese military occupation |
| Leader1: | Norodom Sihanouk |
| Year Leader1: | 1945 |
| Title Leader: | Monarch |
| Deputy1: | Norodom Sihanouk |
| Year Deputy1: | 1945 |
| Deputy2: | Son Ngoc Thanh |
| Year Deputy2: | 1945 |
| Title Deputy: | Prime Minister |
| Today: | Cambodia |
| Demonym: | Kampuchean |
The Kingdom of Kampuchea (km|ព្រះរាជាណាចក្រកម្ពុជា; ja|カンボジア王国) was a short-lived puppet state of Imperial Japan, which existed from 9 March 1945 to 16 October 1945.
On 9 March 1945, during the closing stages of World War II, Japan overthrew the French rule in Indochina. The French colonial administrators were relieved of their positions, and French military forces were ordered to disarm. The Japanese hoped to revive the flagging support of local populations for Tokyo's war effort by encouraging indigenous rulers to proclaim independence.[1] On 13 March, the young King Norodom Sihanouk proclaimed an independent Kingdom of Kampuchea (while changing the official name of the country in French from Cambodge to Kampuchea) following a formal request by the Japanese. Shortly thereafter the Japanese government nominally ratified the independence of Cambodia and established a consulate in Phnom Penh.[2] Sihanouk's decree did away with previous French-Cambodian treaties and he pledged his newly independent country's cooperation and alliance with Japan.[3] The new government did away with the romanization of the Khmer language that the French colonial administration was beginning to enforce and officially reinstated the Khmer script. This measure taken by the short-lived governmental authority would be popular and long-lasting, for since then no government in Cambodia has tried to romanise the Khmer language again. Other changes included the reinstating of the Buddhist lunar calendar.
Norodom Sihanouk initially also served as a prime minister from 18 March 1945. However, Son Ngoc Thanh, another of the men behind the Khmer-language newspaper Nagara Vatta who had fled to Japan following the 1942 anti-French demonstrations, had returned in April 1945 to serve as foreign minister. Son Ngoc Thanh would take over the position of prime minister following the surrender of Japan, serving until French restoration in October 1945.[4]
The Japanese occupation of Cambodia ended with the official surrender of Japan in August 1945. After Allied military units entered Cambodia, the Japanese military forces present in the country were disarmed and repatriated. The French were able to reimpose the colonial administration in Phnom Penh in October the same year. After arresting Son Ngoc Thanh for collaboration with the Japanese on 12 October, the French colonial authorities exiled him to France, where he lived under house arrest. Some of his supporters went underground and escaped to Thai-controlled northwestern Cambodia, where they were eventually to join forces in a pro-independence group, the Khmer Issarak. This anti-French, politically heterogeneous nationalist movement was organised with Thai backing, but would later split into factions.[5]
See also: List of heads of state of Cambodia and List of prime ministers of Cambodia.