At the end of its “working” life, the Ho Chi Minh Trail had grown from a rough assemblage of animal tracks and jungle paths to become a highly effective logistical network stretching from near Vinh, north of the Seventeenth Parallel, to Tay Ninh Province on the edge of the Mekong Delta. Initially it took up to six months to walk the trail from north to south, most of the time travelling at night while carrying rations of rice and salt, medicines and equipment; in four years one man, Nguyen Viet Sinh, is reputed to have carried more than fifty tonnes and covered 40,000km, equivalent to walking round the world. By 1975, however, the trail – comprising at least three main arteries plus several feeder roads leading to various battlefronts and totalling over 15,000km – was wide enough to take tanks and heavy trucks, and could be driven in just one week. It was protected by sophisticated anti-aircraft emplacements and supported by regular service stations (fuel and maintenance depots, ammunition dumps, food stores and hospitals), often located underground or in caves and all connected by field telephone. Eventually there was even an oil pipeline constructed alongside the trail to take fuel south from Vinh to a depot at Loc Ninh. All this absorbed thousands of men and women in maintenance work, as engineers, gunners and medical staff, while as many as fifty thousand Youth Volunteers repaired bridges and filled in bomb craters under cover of darkness.
The trail was conceived in early 1959 when General Giap ordered the newly created Logistical Group 559 to reconnoitre a safe route by which to direct men and equipment down the length of Vietnam in support of Communist groups in the south. Political cadres blazed the trail, followed in 1964 by the first deployment of ten thousand regular troops, and culminating in the trek south of 150,000 men in preparation for the 1968 Tet Offensive. It was a logistical feat that rivalled Dien Bien Phu in both scale and determination: this time it was sustained over fifteen years and became a symbol to the Vietnamese of both their victory and their sacrifice. For much of its southerly route the trail ran through Laos and Cambodia, sometimes on paths forged during the war against the French, sometimes along riverbeds and always through the most difficult, mountainous terrain plagued with leeches, snakes, malaria and dysentery.
On top of all this, people on the trail had to contend with almost constant bombing. By early 1965, aerial bombardment had begun in earnest, using napalm and defoliants as well as conventional bombs, to be joined later by carpet-bombing B-52s. Every day in the spring of 1965 the US Air Force flew an estimated three hundred bombing raids over the trail and in eight years dropped over two million tonnes of bombs, mostly over Laos, in an effort to cut the flow. Later they experimented with seismic and acoustic sensors to eavesdrop on troop movements and pinpoint targets, but the trail was never completely severed and supplies continued to roll south in sufficient quantities to sustain the war.