North Vietnamese invasion of Laos in the context of "Pathet Lao"

The Vietnam War (1 November 1955 – 30 April 1975) was an armed conflict in Vietnam, Laos, and Cambodia fought between North Vietnam (Democratic Republic of Vietnam) and South Vietnam (Republic of Vietnam) and their allies. North Vietnam was supported by the Soviet Union and China, while South Vietnam was supported by the United States and other anti-communist nations. The conflict was the second of the Indochina wars and a proxy war of the Cold War between the Soviet Union and US. The Vietnam War was one of the postcolonial wars of national liberation, a theater in the Cold War, and a civil war, with civil warfare a defining feature from the outset. Direct US military involvement escalated from 1965 until its withdrawal in 1973. The fighting spilled into the Laotian and Cambodian Civil Wars, which ended with all three countries becoming communist in 1975.

After the defeat of the French Union in the First Indochina War that began in 1946, Vietnam gained independence in the 1954 Geneva Conference but was divided in two at the 17th parallel: the Viet Minh, led by Ho Chi Minh, took control of North Vietnam, while the US assumed financial and military support for South Vietnam, led by Ngo Dinh Diem. The North Vietnamese supplied and directed the Viet Cong (VC), a common front of dissidents in the south which intensified a guerrilla war from 1957. In 1958, North Vietnam invaded Laos, establishing the Ho Chi Minh trail to supply the VC. By 1963, the north had covertly sent 40,000 soldiers of its People's Army of Vietnam (PAVN), armed with Soviet and Chinese weapons, to fight in the insurgency in the south. President John F. Kennedy increased US involvement from 900 military advisors in 1960 to 16,000 in 1963 and sent more aid to the Army of the Republic of Vietnam (ARVN), which failed to produce results. In 1963, Diem was killed in a US-backed military coup, which added to the south's instability.

The Royal Lao Armed Forces (Lao: ກອງທັບຣາຊອານາຈັກລາວ; French: Forces Armées du Royaume), best known by its French acronym FAR, were the official military of the Kingdom of Laos, a state that existed from 1949 to 1975 in what is now the Lao People's Democratic Republic. First created under the French protectorate of Laos on July 1, 1949, the FAR was responsible for the defense of the Kingdom since its independence in October 1953 from France, until its dissolution on December 2, 1975. It operated notably during the North Vietnamese invasion of Laos and the Laotian Civil War from 1960 to 1975.

The Ho Chi Minh Trail (Vietnamese: Đường mòn Hồ Chí Minh), also called Annamite Range Trail (Vietnamese: Đường Trường Sơn) was a logistical network of roads and trails that ran from North Vietnam to South Vietnam through the kingdoms of Laos and Cambodia. The system provided support, in the form of manpower and materiel, to the Viet Cong (or "VC") and the People's Army of Vietnam (PAVN), during the Vietnam War. Construction for the network began following the North Vietnamese invasion of Laos in July 1959. At the time it was believed to be the main supply route, however it later transpired that the Sihanouk Trail which ran through Cambodia was handling significantly more material.

It was named by the U.S. after the North Vietnamese leader Hồ Chí Minh. The origin of the name is presumed to have come from the First Indochina War, when there was a Viet Minh maritime logistics line called the "Route of Ho Chi Minh", and shortly after late 1960, as the present trail developed, Agence France-Presse (AFP) announced that a north–south trail had opened, and they named the corridor La Piste de Hồ Chí Minh, the 'Hồ Chí Minh Trail'. The trail ran mostly in Laos, and was called the Trường Sơn Strategic Supply Route (Đường Trường Sơn) by the communists, after the Vietnamese name for the Annamite Range, a major mountain range of central Vietnam. They further identified the trail as either West Trường Sơn (Laos) or East Trường Sơn (Vietnam). According to the U.S. National Security Agency's official history of the war, the trail system was "one of the great achievements of military engineering of the 20th century". The trail was able to effectively supply troops fighting in the south, an unparalleled military feat, given it was the site of the single most intense air interdiction campaign in history.