This brief chronology of major events leading up to and after the Khmer Rouge regime is adopted from Elizabeth Becker’s (1986), When the War Was Over: Cambodia and the Khmer Rouge Revolution (New York: Public Affairs). The formation and milestones of the Extraordinary Chambers in the Courts of Cambodia is adapted from the Court's Timeline of Key Events, accessed from 


King Norodom signs treaties beginning the era of the French Protectorate over Cambodia, lasting until 1953


Sihanouk is crowned king by Vichy French


In Bangkok Cambodians have established Issarak (Freedom) committees against the French


The First Indochina War begins between Ho Chi Minh’s Vietminh army and the French


The Khmer People’s Revolutionary Party is created out of the Indochinese Communist Party


Sihanouk wins limited independence from France


Sihanouk wins complete control over an independent Cambodia. Cambodian communist leader Son Ngoc Minh and roughly half of the Cambodian communist movement go into exile in North Vietnam


Cambodia holds elections. Sihanouk abdicates in favor of his father, forms his own party and sweeps the election


At a congress in Phnom Penh the communist found a Cambodian Marxist-Leninist party, the Workers Party of Kampuchea (to be renamed the Communist Part of Kampuchea in 1971)


At a second party congress, Saloth Sar (the future Pol Pot) becomes head of the Communist party


The US sends combat troops into Vietnam; Sihanouk breaks relations with the US


Sihanouk allows Vietnamese communist use of border areas and seaport


Peasant-led insurrection in northwest Cambodia against rice tax sparks communist decision to wage armed struggle against Sihanouk


Sihanouk wages war, with 35,000-strong national army, against small Khmer Rouge, with fighting force of 5,000


US mounts secret, illegal bombing campaign against Vietnam targets inside Cambodian border area


Sihanouk is deposed by U.S. backed General Lon Nol, establishing the Khmer Republic. Sihanouk flees to China. Within the week, he announces the formation in exile of the Royal Government of the National United Front of Kampuchea, which includes the Khmer Rouge, and over which he serves as head of state. Civil war ensures for the next five years.


The North Vietnamese army continues fighting the Phnom Penh army with the Khmer Rouge build their forces. In December, the North Vietnamese defeat the Cambodian army.


Lon Nol, backed by the US, is elected president of the Khmer Republic


The Paris Agreement on ending the war in Vietnam is signed, thought the Cambodian communists refuse to negotiate. The Khmer Rouge take over the majority of the fighting in Cambodia while the Vietnamese communists retreat to border areas. The US resumes an intensive campaign of bombing Cambodia, with the US Congress forcing and end to the bombing campaign on August 15.

The Khmer Rouge order the creation of cooperatives in all of their zones


Last full year of the Cambodian war. The Khmer Rouge win control over the insurgency movement, purging communist returned from North Vietnam and ethnic Vietnamese as well as Sihanoukists


The Khmer Rouge march into Phnom Penh on New Year’s Day, April 17, and immediately order the evacuation of the capital.

Khmer Rouge revolution concentrates on establishing all people in rural cooperatives. By July, the communist have begun setting up party and government offices in Phnom Penh. At the end of the year, the communist order the second evacuation of city people from the southwest to the northwest and other northerly points.

Prince Sihanouk and his wife return, at the invitation of the Khmer Rouge leadership, in September, and he is sent to the United Nations to claim Cambodia’s seat at the General Assembly. By the end of the regime, Prince Sihanouk will lose about 20 members of his family, at least seven other members of the royal family will be executed at S-21 (Tuol Sleng) prison (Khamboly, 2007, p. 20).


Sihanouk resigns as head of state,  and he and his family are put under house arrest in a small villa in the Royal Palace compound (Khamboly, 2007, 21). The government of the Democratic Kampuchea is publicly announced, headed by “Pol Pot” as prime minister. A constitution is promulgated. The execution of party figures over the question of party ties to Vietnam begins, and the communist complete their purge of the Northern Zone by the year’s end.


On the eve of visit to China, Pol Pot publicly announces the exitence of the Communist Party of Kampuchea (until then secretly operating under the name of Angkar) and his own position as prime minister of Democratic Kampuchea (Khamboly, 2007, p. 22). The party has nearly completed purging leaders of the old society and steps up purges of people within the party. Purge of the Northwestern Zone begins. A border war with Vietnam is initiated, and Cambodia suspends relations with Vietnam on 31 December.


Purge of he Eastern Zone. In December, Vietnam radio announces the formation of a Cambodian national salvation front opposed to the Pol Pot regime, and on 22 December Vietnam launches its offensive.


The Vietnamese-backed National Front for Solidarity and Liberation of Cambodia captures Phnom Penh on 7 January, and the next day announce the establishment of the People’s Revolutionary Council to rule Cambodia as the People’s Republic of Kampuchea. Prince Sihanouk flees the country. Pol Pot and the Cambodian communists loyal to him regroup along the Thai-Cambodian border and, with support of China, wage guerrilla war against the Vietnamese army occupying Cambodia.  In October, the Khmer Rouge government of Democratic Kampuchea retains Cambodia’s seat at the United Nations, even as the UN annually demands Vietnamese withdrawal from Cambodia.


Under pressure from China and the US, the non-communist resistance forces loyal to Prince Sihanouk agree to join the Khmer Rouge in a new Coalition Government of Democratic Kampuchea, sponsored by ASEAN. The fighting continues.


Vietnam and Indonesia call for talks among all Cambodia warring parties. In December, Prince Sihanouk and Vietnamese-backed Prime Minister Hun Sen meet in their first encounter to discuss a peace settlement.


Vietnam withdraws its high command from Cambodia and turns over the running of the war to Phnom Penh officials. Soon after, Sihanouk resigns from the resistance saying the Khmer Rouge is killing his soldiers.


With the Khmer Rouge resistance supported by China, and the anti-Vietnamese occupation resistance supported by Thailand, Vietnam pulls out the last of its troops by late September, and the French host an International Conference on Cambodia in August in Paris–but talks break down. The country changes its name to State of Cambodia.


In January, the five permanent members of the UN Security Council (US, China, France, UK, and the Soviet Union) meet in Paris to negotiate settlement to the Cambodian crisis and to use the UN to effect a solution. The so-called P-5 formula calls for the establishment of the UN Transitional Authority in Cambodia (UNTAC) and a Supreme National Council of the Cambodian parties.


A cease-fire goes into effect in Cambodia. Sihanouk is made chair and Hun Sen vice chair of the Cambodian Supreme National Council. The peace plan is approved at the second Paris International Conference on Cambodia, and Prince Sihanouk returns to Phnom Penh for the first time since he fled in January 1979. Khmer Rouge leader Khieu Samphan (now on trial for crimes against humanity) is forced to flee the capital after being rushed by a mob. By December, the first officials for UNTAC arrive in Cambodia.


Under UNTAC, the UN High Commissioner for Refugees oversees the repatriation of some 370,000 refugees from Thailand. By year’s end, UNTAC has registered 4.8 million voters for elections the next year.


Some 20 political parties register to take part in the elections, thought the Khmer Rouge abstain. On 23 May, election day proceeds with nearly 90 percent voter turnout. Victorious is the party of Prince Norodom Ranariddh, son of Prince Sihanouk, with 48 percent of the vote. Hun Sen’s party takes 38 percent of vote. Under pressure and intimidation, Prince Ranariddh agrees to share power with Hun Sen, Sihanouk is crowned king, the constitution is ratified, and the country changes its name to the Kingdom of Cambodia.


Ieng Sary (now under trial for crimes against humanity) brokers a deal with Hun Sen, approved by Prince Ranariddh, that allows him to defect to the government side with his soldiers and retain control over an area around Palin.


Pol Pot orders the murder of his top aide. By now, more than half of the Khmer Rouge soldiers have defected to the government. With calls from foreign governments, led by the US, for the Khmer Rouge leaders to hand over Pol Pot, the Khmer Rouge publicly display Pol Pot for the first time since 1979 in a show trial meant to demonstrate that Pol Pot is not longer in power. In October, jounalist Nate Thayer is granted an interview Pol Pot, who refuses to acknowledge any wrongdoing. 

Norododom Ranariddh and Hun Sen, the Cambodian Co-Prime Ministers at the time, request United Nations assistance in organizing the process for the Khmer Rouge trials.


On April 15, the few remaining Khmer Rouge leaders announce that Pol Pot has died in his sleep of a heart attack; he is cremated three days later.


The "Law on the Establishment of the Extraordinary Chambers in the Courts of Cambodia for the Prosecution of Crimes Committed during the Period of Democratic Kampuchea" is passed by the National Assembly, approved by the Senate and Constitutional Council, and signed by His Majesty King Norodom Sihanouk.  


The "Agreement between the United Nations and the Royal Government of Cambodia concerning the Prosecution under Cambodian Law of Crimes Committed during the period of Democratic Kampuchea", enters into force.


Judges and co-prosecutors are sworn in and first staff members take up duties at the Extraordinary Chambers in the Courts of Cambodia (ECCC).  


Kaing Guek Eav, Nuon Chea, Ieng Thirith, Ieng Sary and Khieu Samphan are arrested and placed under provisional detention, charged with crimes against humanity and grave breaches of the 1949 Geneva Conventions.


Opening Statements of Case 001 to try Kaing Guek Eav, alias Duch, who headed the notorious S-21 prison and execution center.


Kaing Guek Eav, alias Duch, found guilty of crimes against humanity and grave breaches of the 1949 Geneva conventions.


Opening Statements of Case 002 to try Nuon Chea, Ieng Thirith, Ieng Sary and Khieu Samphan for crimes against humanity and grave breaches of the 1949 Geneva Conventions.


Kaing Guek Eav, alias Duch, is sentenced to life imprisonment by the Supreme Court Chamber of the ECCC.

Ieng Thirith, accused in Case 002, is determined unfit to stand trial due to medical reasons and is released from detention.

King Sihanouk dies in October while in Beijing for medical treatments. After a three-month mourning period, he is cremated during a four-day funeral ceremony in a newly constructed pagoda on the lawn of the National Museum.