This Vietnam War timeline has been compiled by Alpha History authors. It lists significant events in Cambodia, particularly those related to the conflict in Vietnam. If you would like to suggest an event or date or this timeline, please contact Alpha History.
Cambodia is annexed by its eastern neighbour Vietnam.
Cambodian Khmers revolt against Vietnamese rule.
Cambodia successfully overthrows Vietnamese rule.
October 19th: Prince Norodom, 26, becomes king of Cambodia, following the death of Ang Duong.
Facing a Cham rebellion, King Norodom seeks the support of the French.
July 15th: A treaty between France and Siam (Thailand) transfers Cambodia to French colonial rule.
June 17th: Using gunboat diplomacy, the French force King Norodom to sign a treaty surrendering control of taxes and trade in Cambodia.
October 17th: A decree formalises the creation of French Indochina, a colonial union of Tonkin, Annam, Cochinchina and Cambodia.
France’s résident supérieur (governor) in Cambodia is given sweeping powers, including the authority to rule by decree.
October 31st: Future Cambodian king, president and prime minister Norodom Sihanouk is born in Phnom Penh.
May 19th: Saloth Sar, later to lead the Khmer Rouge and Kampuchea as Pol Pot, is born to a family of peasant fishermen in north-eastern Cambodia.
August: Japanese troops enter Cambodia and occupy it with several thousand troops. The French colonial regime is allowed to keep functioning.
November 9th: Cambodia is granted independence from France.
December 14th: Cambodia is granted membership of the United Nations.
September 28th: Leaders of the Khmer People’s Revolutionary Party (KPRP) hold a three day congress in Phnom Penh. They vote to reform as the Workers’ Party of Kampuchea (WPK).
February: Against a backdrop of student unrest, Saloth Sar is elected as party secretary of the WPK.
July: Saloth and other WPK leaders flee Phnom Penh to north-east Cambodia, in order to establish guerrilla bases and expand the party.
March 18th: United States forces begin Operation Menu, a secret bombing campaign against North Vietnamese Army (NVA) and Viet Cong troops in Laos and eastern Cambodia.
May 9th: An article in the New York Times exposes Nixon’s bombing of Cambodia and Laos.
March 18th: The Cambodian national assembly votes to remove Norodom Sihanouk as the nation’s head of state.
March 23rd: Norodom Sihanouk speaks on Chinese radio and calls for a nationwide uprising against Lon Nol and his supporters. This sparks days of violent protest in Cambodia.
March 26th: Several officials, including two National Assembly deputies and Lon Nol’s policeman brother, are killed by Sihanouk supporters.
March 29th: The North Vietnamese Army (NVA) attack Cambodian forces, in retaliation for the deposition of Sihanouk. NVA forces occupy large parts of eastern Cambodia, temporarily reaching the outskirts of Phnom Penh.
The Khmer Rouge receives weapons, supplies and training from both North Vietnam and the Viet Cong.
March 10th: With the Cambodian assembly about to pass a new constitution, president Lon Nol suspends the process.
June 4th: Lon Nol is elected president of the Khmer Republic, following elections that international observers declare to be rigged.
January 29th: President Lon Nol declares a unilateral ceasefire across Cambodia, including a halt to US bombing runs.
February 7th: Khmer Rouge forces, ignoring Lon Nol’s ceasefire, lay siege to the city of Kompong Thom. This leads to the resumption of American bombing operations.
March: Facing an escalation in attacks by the Khmer Rouge, Lon Nol introduces conscription.
March 17th: Lon Nol’s police storm a protest of striking university teachers and students, throwing grenades into the crowd. Two people are killed.
March 17th: So Photra, a son-in-law of Norodom Sihanouk, steals an American plane and drops several bombs in the region of Lon Nol’s presidential palace. Lon Nol is unharmed but 43 people are killed.
March 18th: Lon Nol responds to the previous day’s events by suspending civil rights, preventing assemblies and arresting several members of the royal family.
April 24th: Lon Nol announces the suspension of the National Assembly and the formation of a high council that will rule by decree, for a period of six months.
August 15th: The US brings Operation Freedom Deal (the bombing of Khmer Rouge and North Vietnamese Army positions in Cambodia) to an end. Some 250,000 tons of American bombs have been dropped on Cambodia in three years.
March: The Khmer Rouge captures the former royal capital of Oudong, some 25 miles from Phnom Penh. Government forces recapture Oudong in July.
April 2nd: Khieu Samphan, a Khmer Rouge official, meets with Chinese leader Mao Zedong.
May 26th: China agrees to provide Khmer Rouge forces with military equipment and supplies.
July 1st: Khmer Rouge soldiers execute around 700 civilians and surrendered soldiers in Battambang province.
January: The Khmer Rouge receives around 4,000 tons of weapons and ammunition from North Vietnam.
February: Saloth Sar and his inner circle decide that cities occupied by the Khmer Rouge would be cleared of civilians.
March 8th: Khmer Rouge rocket attacks force the suspension of all civilian flights in and out of Phnom Penh airport.
April 8th: Cambodia’s prime minister, Long Boret, attempts to initiate ceasefire talks with the Khmer Rouge. He is ignored.
April 12th: US Marines commence Operation Eagle Pull, a mission to airlift Americans and other foreign nations from Phnom Penh.
April 17th: Khmer Rouge forces capture Phnom Penh. Surrendering soldiers and government officials, including prime minister Long Boret, are immediately executed.
April 18th: The Khmer Rouge begins the evacuation of Phnom Penh and other Cambodian cities, forcing even the sick, wounded and elderly to leave by foot.
April 27th: Khmer Rouge leader Khieu Samphan says “the important winners are the people… they will have an independent, peaceful, neutral, sovereign, non-aligned Cambodia with territorial integrity”.
May 1st: Khmer Rouge forces invade the Vietnamese island of Phu Quoc and claim it as part of Cambodia.
May 5th: US intelligent reports claim that dozens of Cambodian military officers and their wives have been executed.
May 10th: The Khmer Rouge occupies the Vietnamese island of Tho Chu and kills around 500 civilian residents.
May 12th: A Khmer Rouge gunboat seizes an American cargo vessel, SS Mayaguez, in the Gulf of Thailand.
May 14th: US Marines launch a mission to rescue the crew of SS Mayaguez, landing on the Cambodian island of Koh Tang and engaging the Khmer Rouge. The crewmen are eventually rescued but 38 American soldiers are killed.
May 20th: The Khmer Rouge holds a five-day long congress in a sports venue in Phnom Penh, attended by hundreds of party leaders, military officers and cadres. They are ordered to evacuate all cities and towns, execute all leaders and officials of the old regime, close markets, abolish all currency, suppress all religious activity and close Cambodia’s borders.
May 24th: Vietnamese forces mobilise and eventually recapture Phu Quoc and Tho Chu.
July 21st: Almost 300 Cambodian refugees are gunned down by Khmer Rouge soldiers as they attempt to cross the border into Thailand.
August: Chao Ponhea Yat High School in Phnom Penh is seized by the Khmer Rouge and converted into a prison and interrogation facility. It is later named S-21 (‘Security Prison 21’).
December 31st: Norodom Sihanouk returns to Cambodia after several years in exile following the 1970 coup.
January 5th: The Khmer Rouge regime proclaims the Constitution of Democratic Kampuchea.
February 17th: French newspaper Le Monde reports the Khmer Rouge has executed all officials of the old regime, as well as hundreds of intellectuals.
February 25th: A North Vietnamese jet bombs the Cambodian city of Siem Reap, killing at least 15 people. Both the Vietnamese and Cambodian governments blame the United States for this attack.
March 20th: The Khmer Rouge holds national elections. Under the terms of the January constitution the new state has universal suffrage, however millions of Cambodians are not permitted to vote.
April 2nd: Distraught by the Khmer Rouge’s genocidal policies, Norodom Sihanouk resigns as head of state. He remains under house arrest until late 1978.
April 8th: A series of unexplained explosions are reported in Phnom Penh.
April 14th: Saloth Sar, the Khmer Rouge’s ‘Brother Number One’, is appointed prime minister of Democratic Kampuchea. He begins using the pseudonym Pol Pot.
April 17th: Vietnamese leaders congratulate Pol Pot and his fellow Khmer Rouge leaders on their appointments.
May: Khmer Rouge security chief Kang Kek Iew (‘Comrade Duch’) moves his headquarters to the notorious S-21 centre for detention, torture and execution.
September 8th: The death of Chinese communist leader Mao Zedong.
December 20th: A Khmer Rouge speech describes enemies of the party as “microbes” that cause “sickness”, so must be purged.
April: A coup attempt against Pol Pot and other Khmer Rouge leaders is thwarted. Those involved are all executed.
April 10th: Hu Nim, an outspoken member of the Khmer Rouge government, is arrested. He dies in the S21 prison some three months later.
May 3rd: The United States Congress begins a hearing into claims of genocide in Cambodia.
June 6th: American academic Noam Chomsky claims that stories of mass murder in Cambodia were “propaganda” and greatly exaggerated.
June: Hun Sen, a Khmer Rouge commander, defects to Vietnam with around 200 men.
July: During a speech in Cambodia’s western region, a Khmer Rouge spokesman says that the party had purged its own members to remove those of “bad composition”.
December 31st: Cambodia severs political and diplomatic relations with Vietnam.
April 18th: Khmer Rouge forces cross the border into south-western Vietnam and attack the village of Ba Chuc, killing 3,157 civilians.
June 30th: The International Federation of Human Rights issues a report accusing the Cambodian regime of mass executions, forced labour, torture and intentional famine.
August 13th: Three foreign sailors (a Briton, a Canadian and a New Zealander) drift into Cambodian waters and are captured by Khmer patrol boats. All are executed.
December 23rd: Malcolm Caldwell, a British academic who supported the Khmer Rouge, is assassinated in Phnom Penh, hours after meeting Pol Pot.
December 25th: Around 150,000 Vietnamese soldiers invade Cambodia.
January 5th: Pol Pot gives Norodom Sihanouk permission to leave Cambodia, provided he speaks at the United Nations and denounces the Vietnamese invasion.
January 6th: As the Vietnamese approach Phnom Penh, S-21 commandant Kang Kek Iew executes all remaining prisoners, on the orders of the government.
January 6th: In New York, Sihanouk tells the press that Pol Pot “treats the Cambodian people as cattle good for forced labour and pigs good for the slaughterhouse”.
January 7th: Vietnamese forces gain control of Phnom Penh, ending almost four years of Khmer Rouge rule.
January 10th: The formation of the People’s Republic of Kampuchea, a socialist state aligned with Vietnam and the Soviet Union.
June 15th: Two French doctors claim that bubonic plague was breaking out in Cambodia and that the country had only 40 native doctors.
July 15th: The new Cambodian government moves to place Pol Pot and Ieng Sary on trial for genocide.
August 7th: United Nations and Red Cross officials predict that a further two million Cambodians will die from starvation, due to the ravages of the Khmer Rouge regime.
September 13th: British-Australian journalist John Pilger publishes a story claiming the Khmer Rouge have killed as many as two million Cambodians.
November 15th: The United Nations General Assembly passes a resolution calling for the withdrawal of Vietnamese troops from Cambodia.
October 23rd: After talks in Paris, Cambodian political groups sign a peace accord and agree to free elections. The Khmer Rouge refuses to participate in the elections or to demobilise their remaining forces.
May 23rd: UN-supervised elections commence in Cambodia.
September 24th: Following nationwide elections, the Royal Government of Cambodia is formed. Norodom Sihanouk is returned as king, though his power is limited by a constitution.
July: Khmer Rouge officials place Pol Pot on trial for a range of charges, including treason and orchestrating the murder of Son Sen. He is convicted and sentenced to life under house arrest.
April 15th: Pol Pot (Saloth Sar) dies in Anlong Veng, near Cambodia’s northern border. He was 72.
June 6th: The Khmer Rouge War Crimes Tribunal is established by the Cambodian government and the United Nations.
July 26th: Kang Kek Iew, better known as the notorious S-21 commandant Comrade Duch, is sentenced to 35 years imprisonment. In February 2012 this is extended to a life sentence.
August 7th: Nuon Chea, the most senior surviving leader of the Khmer Rouge, is convicted of crimes against humanity and sentenced to life imprisonment.