The Laotian Civil War was waged between the Communist Pathet Lao and the Royal Lao Government from 23 May 1959 to 2 December 1975. The Kingdom of Laos was a covert theater during the Vietnam War with both sides receiving heavy external support in a proxy war between the global Cold War superpowers. The fighting also involved the North Vietnamese, South Vietnamese, American and Thai armies, both directly and through irregular proxies. The war is known as the "Secret War" among the American CIA Special Activities Center, and Hmong and Mien veterans of the conflict.

The Franco–Lao Treaty of Amity and Association (signed 23 October 1953) transferred remaining French powers to the Royal Lao Government (except control of military affairs), establishing Laos as an independent member of the French Union. However, this government did not include representatives from the left wing of the Lao Issara anti-colonial armed movement. The following years were marked by a rivalry between the neutralists under Prince Souvanna Phouma, the right wing under Prince Boun Oum of Champassak, and the left-wing Lao Patriotic Front under Prince Souphanouvong and half-Vietnamese future Prime Minister Kaysone Phomvihane. Several attempts were made to establish coalition governments, and a "tri-coalition" government was finally seated in Vientiane.

The North Vietnamese Army, in collaboration with the Pathet Lao, invaded Laos in 1958 and 1959, occupying the east of the country to use for its Ho Chi Minh trail supply corridor and as a staging area for offensives into South Vietnam. There were two major theatres of the war, one for control over the Laotian Panhandle and the other was fought around the northern Plain of Jars. From 1961 onward, the US trained Hmong tribesmen to disrupt North Vietnamese operations and in 1964, the US began bombing North Vietnamese supply routes.

The North Vietnamese and Pathet Lao eventually emerged victorious in December 1975, following from North Vietnam's final victory over South Vietnam in April 1975. The conflict killed tens of thousands of people including many thousands of North Vietnamese soldiers. Unexploded ordnance (UXO), mostly from US bombing, remains a problem. According to the Laotian government in 2017, there were 29,522 deaths and 21,048 injuries from explosive ordnance during the war or as result of UXO since the end of the war.

After the communist takeover in Laos, up to 300,000 people fled to neighbouring Thailand, and Hmong rebels began an insurgency against the new government. The Hmong were persecuted as traitors, with the Laotian government and its Vietnamese allies carrying out human rights abuses against Hmong civilians. The incipient conflict between Vietnam and China also played a role with Hmong rebels being accused of receiving support from China. Over 40,000 people died in the conflict. The Lao royal family were arrested by the Pathet Lao and sent to labor camps, where most of them died in the late 1970s and 1980s, including King Savang Vatthana, Queen Khamphoui and Crown Prince Vong Savang.

Overview

The 1954 Geneva Conference established Laotian neutrality. The People's Army of Vietnam (PAVN), however, continued to operate in both northern and southeastern Laos. There were repeated attempts from 1954 onward to force the North Vietnamese out of Laos, but regardless of any agreements or concessions, Hanoi had no intention of withdrawing from the country or abandoning its Laotian communist allies.

North Vietnam established the Ho Chi Minh trail as a paved highway in southeast Laos paralleling the Vietnamese border. The trail was designed to transport North Vietnamese troops and supplies to South Vietnam, as well as to aid the National Liberation Front (Viet Cong).

North Vietnam also had a sizable military effort in northern Laos, while sponsoring and maintaining an indigenous communist rebellion, the Pathet Lao, to put pressure on the Royal Lao Government.

The U.S. Central Intelligence Agency (CIA), in an effort to disrupt these operations in northern Laos without direct U.S. military involvement, responded by training a guerrilla force of about 30,000 Laotian hill tribesmen known as Special Guerrilla Units (SGUs). Consisting mostly of local Hmong (Meo) tribesmen along with the Mien and Khmu, they were led by Royal Lao Army General Vang Pao, a Hmong military leader. This army, supported by the CIA's proprietary airline Air America, Thailand, the Royal Lao Air Force, and a covert air operation directed by the United States ambassador to Laos, fought the People's Army of Vietnam, the National Liberation Front (NLF), and their Pathet Lao allies to a seesaw stalemate, greatly aiding U.S. interests in the war in Vietnam.

The status of the war in the north throughout the year generally depended on the weather. As the dry season started, in November or December, so did North Vietnamese military operations, as fresh troops and supplies flowed down out of North Vietnam on newly passable routes, either down from Dien Bien Phu, across Phong Saly Province on all-weather highways, or on Route 7 through Ban Ban, Laos on the northeast corner of the Plain of Jars. The CIA's covert operations clandestine army would give way, harrying the PAVN and Pathet Lao as they retreated; Raven Forward Air Controllers would direct massive air strikes against the communists by USAF jets and RLAF T-28s to prevent the capture of the Laotian capitals of Vientiane and Luang Prabang. When the rainy season six months later rendered North Vietnamese supply lines impassable, the Vietnamese communists would recede toward Vietnam.

The war in the southeastern panhandle against the Ho Chi Minh trail was primarily a massive air interdiction program by the USAF and United States Navy because political constraints kept the trail safe from ground assault from South Vietnam. Raven FACs also directed air strikes in the southeast. Other Forward Air Controllers from South Vietnam, such as Covey FACs from the 20th Tactical Air Support Squadron and Nail FACs from the 23rd Tactical Air Support Squadron, also directed strikes. Other air strikes were planned ahead. Overall coordination of the air campaign was directed by an Airborne Command and Control Center, such as those deployed in Operation Igloo White.

The existence of the conflict in Laos was sometimes reported in the U.S., and described in press reports as the CIA's "Secret War in Laos" because details were largely unavailable due to official government denials that the war existed. The denials were seen as necessary considering that the North Vietnamese government and the U.S. had both signed agreements specifying the neutrality of Laos. U.S. involvement was considered necessary because North Vietnam had effectively gained control over a large part of the country. Despite these denials, however, the civil war was the largest U.S. covert operation prior to the Soviet–Afghan War, with areas of Laos controlled by North Vietnam subjected to years of intense U.S. aerial bombardment, representing the heaviest bombing campaign in history. Overshadowing it all was the struggle of the Cold War, with the United States' policy of the containment of communism and the policies of the People's Republic of China and the Soviet Union of spreading communism via subversion and insurgency.

Chronology of the Laotian Civil War

1945: Prelude to war The end of World War II left Laos in political chaos. The French, who had been displaced from their protectorate by the Japanese, wanted to resume control of Laos, and sponsored guerrilla forces to regain control. The Japanese had proclaimed Laos independent even as they lost the war. Though King Sisavang Vong thought Laos was too small for independence, he had proclaimed the end of the French protectorate status while simultaneously favoring the French return. He let it be known he would accept independence if it should occur. Thus there was a nascent movement for independence amid the turmoil.

Underlying all this was a strong undercurrent of Vietnamese involvement. Sixty percent of the population of Laos' six urban areas were Vietnamese, with the Vietnamese holding key positions in the civil bureaucracies and the police. Since the 1930s the Indochinese Communist Party had established wholly Vietnamese cells in Laos.

Prince Phetsarath Ratanavongsa, as Viceroy and Prime Minister, established the Lao royal treasury account with the Indochinese treasury in Hanoi in an attempt to establish a functional economy.

French commandos parachuted into Laos beginning in 1945 to organize guerrilla forces. By November, they had formed the guerrillas into four light infantry battalions of the newly founded French Union Army. The officers and sergeants of the new Lao battalions were French.

In October 1945, a Lao nationalist movement called Lao Issara (Free Laos) was founded as a new government for Laos. Among Lao Issara's prominent members were three European-educated princes; brothers Phetsarath Ratanavongsa and Souvanna Phouma, and their half brother, Souphanouvong. The former became the titular founder of Lao Issara. Souphanouvong became commander in chief, as well as minister of foreign affairs. Souvanna Phouma became minister of public works.

Independence began with an uprising of the Vietnamese residents in Savannakhet. Prince Souphanouvong took command of a band of partisans armed with weapons looted from the local militia. The band moved northward to the administrative capitol of Vientiane with its provisional revolutionary government. Souphanouvong then urged the signing of a military cooperation treaty with the newly established North Vietnamese communist government, which was done. The French military mission was escorted out of Laos into Thailand by a contingent of Chinese troops.

However, the Lao Issara never gained more than a tenuous hold on the entirety of Laos. Roving Viet Minh detachments ruled the northeast, but the Viet Minh declined to aid the new government. Chinese troops, including the Chinese Nationalist 93rd Division, occupied cities as far south as Luang Prabang. The French-sponsored guerrillas controlled the southern provinces of Savannakhet and Khammouan. Prince Boun Oum, who sympathized with the French, occupied the rest of the southern panhandle.

For these, and other reasons, Lao Issara could not hold the country against the returning French colonial government and its troops. The French negotiated a Chinese withdrawal from Laos prior to their own return, removing them from the field.

1946: French return; Vietnamese arrive In January 1946, the French began the reconquest of Laos by sweeping the Bolovens Plateau. They had organized six battalions of light infantry, to which they added a minor force of French troops.

On 21 March 1946, Souphanouvong and his largely Vietnamese force fought the French Union troops at Savannakhet, to no avail; the attackers mustered paratroopers, artillery, armored cars, and Spitfire fighter-bombers. The Lao Issara troops suffered 700 killed. They fled, leaving behind 250 bodies and 150 prisoners.

On 24 April, the French dropped a paratroop battalion on the outskirts of Vientiane, and took the city without resistance. On 9 May, they repeated their airborne tactics with a drop outside Luang Prabang. This was coupled with a thrust to the north by the French forces, from Vientiane to Luang Prabang, that chased Phetsarath Ratanavongsa and the Lao Issara ministers out of Laos. The king reinstated the French rule by repudiating his actions that had been pressured from him by the Japanese, Chinese, and Lao Issara.

By September 1946, the Lao Issara had been defeated and had fled to exile in Bangkok. One of its splinter groups, led by Thao O Anourack, fled to Hanoi.