The Ho Chi Minh Trail (), also called Annamite Range Trail () 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<!--This word is correct and not a typo. Please do not alter it to material-->, 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". Shortly after late 1960, as the present trail developed, Agence France-Presse (AFP) announced that a north–south trail had opened, naming the corridor La Piste de Hồ Chí Minh, the 'Hồ Chí Minh Trail'. They further identified the trail as either West Trường Sơn (Laos) or East Trường Sơn (Vietnam). The trail effectively supplied troops fighting in the south – an unparalleled military feat, considering it was the site of the single most intense air interdiction campaign in history.
Origins (1959–1965)
Parts of what became the trail had existed for centuries as primitive footpaths that enabled trade. The terrain was among the most challenging in Southeast Asia, a sparsely populated region of rugged mountains in elevation, triple-canopy jungle and dense tropical rainforests. Pre-First Indochina War, the routes were known as the "Southward March", "Eastward March", "Westward March", and "Northward March". Laotian elections in May brought a right-wing government to power in Laos, increasing dependence on U.S. military and economic aid and an increasingly antagonistic attitude toward North Vietnam.
PAVN forces, alongside the Pathet Lao, invaded Laos on 28 July 1959, with fighting all along the border with North Vietnam against the Royal Lao Army (RLA). In September 1959, Hanoi established the 559th Transportation Group, headquartered at Na Kai, Houaphan province in northeast Laos close to the border. It was under the command of Colonel (later General) Võ Bẩm and established to improve and maintain a transportation system to supply the VC insurgency against the South Vietnamese government. Initially, the North Vietnamese effort concentrated on infiltration across and immediately below the Vietnamese Demilitarized Zone (DMZ) that separated the two Vietnams. The 559th Group "flipped" its line of communications to the west side of the Trường Sơn mountains.
Base areas
There were five large base areas in the panhandle of Laos (see map). BA 604 was the main logistical center during the war. From there, the coordination and distribution of men and supplies into South Vietnam's Military Region (MR) I and BAs further south was accomplished.
thumb|upright|Bicycle used by communist forces on the Ho Chi Minh Trail to transport supplies. [[National Museum of American History, Washington, D.C.]]
The system developed into an intricate maze of dirt roads (paved with gravel and corduroyed in some areas), foot and bicycle paths and truck parks. There were numerous supply bunkers, storage areas, barracks, hospitals, and command and control facilities, all concealed from aerial observation by an intricate system of natural and man-made camouflage that was constantly improved. By 1973, trucks could drive the entire length of the trail without emerging from the canopy except to ford streams or cross them on crude bridges built beneath the water's surface. The supply capacity of the trail reached 20 to 30 tonnes per day in 1964 and it was estimated by the U.S. that 12,000 (actually 9,000) PAVN soldiers had reached South Vietnam that year.
The intricacies of Laotian affairs, and U.S. and North Vietnamese interference in them, led to a mutual policy of each ignoring the other, at least in the public eye. This did not prevent the North Vietnamese from violating Lao neutrality by protecting and expanding their supply conduit, and by supporting their Pathet Lao allies in their war against the central government. U.S. intervention came in the form of building and supporting a CIA-backed clandestine army in its fight with the communists and constant bombing of the trail. They also provided support for the Lao government.
Air operations against the trail
thumb|upright=1.5|[[Operation Barrel Roll|Barrel Roll • Steel Tiger • Tiger Hound areas of operations]]
On 14 December 1964, the U.S. Air Force's (USAF) "Operation Barrel Roll" carried out the first systematic bombardment of the Hồ Chí Minh Trail in Laos.
Ground operations against the trail
thumb|[[PAVN troops on the trail (photo taken by a U.S. MACV-SOG team)]]
On the ground, the CIA and the RLA had initially been given the responsibility of stopping, slowing, or, at the very least, observing the enemy's infiltration effort. In Laos, the agency began Operation Pincushion in 1962 to accomplish that goal. This was the beginning of an ever-expanding reconnaissance effort by MACV-SOG that would continue until the operation was disbanded in 1972. Another weapon in the U.S. arsenal was unleashed upon the trail on 10 December 1965, when the first B-52 Stratofortress bomber strike was conducted in Laos.
Despite U.S. anti-infiltration efforts, the estimated number of PAVN infiltrators for 1966 was between 58,000 and 90,000 troops, including five full enemy regiments. In 1967 Senior Colonel (later General) Đồng Sỹ Nguyên assumed command of the 559th Group. In comparison to the above DIA estimate, by the end of the year the North Vietnamese had completed 2,959 km of vehicle capable roads, including 275 kilometers of main roads, 576 kilometers of bypasses, and 450 entry roads and storage areas.
It was learned by U.S. intelligence that the enemy was using the Kong and Bang Fai Rivers to transport food, fuel, and munitions shipments by loading materiel into half-filled steel drums and then launching them into the rivers. They were later collected downstream by nets and booms. Unknown to the U.S., the North Vietnamese had also begun to transport and store more than 81,000 tonnes of supplies "to be utilized in a future offensive".
Operation Commando Hunt (1968–1970)
thumb|upright=1.5|The Ho Chi Minh Trail, 1970.
In the wake of the Tet Offensive, the North Vietnamese expanded and modernized their logistical effort. The number of supply and maintenance personnel dropped, mainly due to increased use of motor and river transport and mechanized construction equipment. The CIA estimated during the year that the 559th Group was using 20 bulldozers, 11 road graders, three rock crushers, and two steamrollers for maintenance and new road construction.
This round-the-clock aerial effort was directed by "Operation Igloo White", run out of Nakhon Phanom, Thailand. It was composed of three parts: strings of air-dropped acoustic and seismic sensors collected intelligence on the trail; computers at the Intelligence Collection Center (ICS) in Thailand collated the information and predicted convoy paths and speeds; and an airborne relay and control aircraft which received the signals from the sensors and routed aircraft to targets as directed by the ICS.
thumb|upright=1.35|The evolution of PAVN [[anti-aircraft weapons, 1965–1972.]]
The North Vietnamese also responded to the American aerial threat by the increased use of heavy concentrations of anti-aircraft artillery. By 1968 this was mainly composed of 37 mm and 57 mm radar-controlled weapons. The next year, 85 mm and 100 mm guns appeared, and by the end of Commando Hunt, over 1,500 guns defended the system. As early as 1969 PAVN had begun its largest logistical effort of the entire conflict.
At first the operation went well, with little resistance from the North Vietnamese. By early March 1971 the situation changed. Hanoi made the decision to stand and fight. It began to muster forces which would eventually number 60,000 PAVN troops as well as several thousand allied Pathet Lao troops and Lao irregulars, outnumbering the ARVN by almost three to one.
The fighting in southeastern Laos was unlike any yet seen in the Vietnam War, since the PAVN abandoned its old hit-and-run tactics and launched a conventional counterattack. The PAVN first launched massed infantry attacks supported by armor and heavy artillery to crush ARVN positions on the flanks of the main advance. Coordinated anti-aircraft fire made tactical air support and resupply difficult and costly, with 108 helicopters shot down and 618 others damaged.
As South Vietnamese forces were on the verge of collapse, President Richard M. Nixon responded by increasing the magnitude of the U.S. air support. Due to the withdrawal of U.S. aviation units from Southeast Asia, squadrons were flown into South Vietnam from Japan and the U.S. itself. The effort failed to halt the fall of Quảng Trị City on 2 May, seemingly sealing the fate of the four northernmost provinces. The North Vietnamese then launched two further attacks from their base areas in Cambodia, the first aimed to seize Kon Tum in the Central Highlands to cut South Vietnam in two; the second provoked a series of battles in and around An Lộc, the capital of Bình Long Province. A total of 14 PAVN divisions were now committed to the offensive. On 13 May 1972, South Vietnam launched a counteroffensive with four divisions backed by massive U.S. air support. By 17 May, Quảng Trị City was retaken, but the South Vietnamese military ran out of steam. The PAVN thrusts against Kon Tum and An Lộc were contained. Due to the adoption of a conventional offensive and the logistical effort needed to sustain it, U.S. airpower was particularly effective and PAVN casualties were high. The North Vietnamese suffered approximately 100,000 casualties while the South Vietnamese suffered 30,000 fatalities during the fighting. Jockeying for control of more territory, both sides flagrantly violated the ceasefire and open hostilities began anew.
Command then devolved upon PAVN Major General Hoàng Thế Thiện. In December 1974 the first phase of a limited PAVN offensive in South Vietnam began. Its success inspired Hanoi to try for an expanded but still limited, offensive to improve its bargaining position with Saigon. In March, General Văn Tiến Dũng launched "Campaign 275", the success of which prompted the general to push Hanoi for a final all-out offensive to take all of South Vietnam.