<P> These supplies traveled in convoys from North Vietnam in relays, with trucks shuttling from only one way - station to the next . The vehicles were then unloaded and reloaded onto "fresh" trucks at each station . If a truck was disabled or destroyed, it was replaced from the assets of the next northern station and so on until it was replaced by a new one in North Vietnam . Eventually, the last commo - liaison station in Laos or Cambodia was reached and the vehicles were unloaded . The supplies were then cached, loaded onto watercraft, or man - portered into South Vietnam . </P> <P> Due to the increased effectiveness of "Commando Hunt", North Vietnamese transportation units usually took to the roads only at dusk with the peak in traffic coming in the early hours of the morning . As American aircraft came on station, traffic would subside until just before dawn, when fixed - wing gunships and night bombers returned to their bases . The trucks then began rolling again, reaching another peak in traffic around 06: 00 as drivers hurried to get into truck parks before sunrise and the arrival of the morning waves of U.S. fighter bombers . By the last phase of "Commando Hunt" (October 1970--April 1972), the average daily number of U.S. aircraft flying interdiction missions included 182 attack fighters, 13 fixed - wing gunships, and 21 B - 52s . </P> <P> 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 . </P> <P> Of all the weapons systems used against the trail, according to the official North Vietnamese history of the conflict, the AC - 130 Spectre fixed - wing gunship was the most formidable adversary . The Spectres "established control over and successfully suppressed, to a certain extent at least, our nighttime supply operations". The history claimed that allied aircraft destroyed some 4,000 trucks during the 1970--71 dry season, of which the C - 130s alone destroyed 2,432 trucks . </P>

What is the importance of ho chi minh trail in the vietnam war