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Synonymous with motorized protection and firepower, gun trucks were feared by the enemy, who dubbed them Mui Hoi Con Rong (Breath of the Dragon) for the awesome fire they delivered.

WHEN THE UNITED STATES committed major ground forces to Vietnam in 1965, truck transport was the most available  and cost-effective means of hauling supplies around the country. Aircraft (fixed and rotary) helped move provisions from South Vietnamese ports to the field, but they could lift only limited tonnage and were already tasked with a variety of other missions. Water transport moved supplies as well, but was necessarily limited to regions served by South Vietnam’s waterways.

Supply responsibilities were allotted to the four corps tactical zones. Based at Da Nang, I Corps stretched from the demilitarized zone to the edge of the Central Highlands. II Corps ran from the Central Highlands south to the provinces around Cam Ranh Bay, with Qui Nhon as its supply center. III Corps spanned the relatively short distance between II Corps and the Mekong Delta, consisting primarily of the provinces near Saigon, its central supply hub. IV Corps encompassed the Mekong Delta region, and Long Binh was its main depot.

In October 1966, the U.S. Army established four motor transportation units to operate under its Transportation Corps in Vietnam: The 57th Transportation Battalion carried materiel in I Corps; the 8th Transportation Group (Motor Transport) moved materiel between Qui Nhon and Pleiku, while also serving An Khe; the 48th Transportation Group serviced the Saigon–Long Binh area, including Bien Hoa and Vung Tau; while the 500th Transportation Group’s area of responsibility spanned from Cam Ranh Bay to the interior of Vietnam. The last three transportation organizations were responsible for performing “line haul”or long-distance transport, as opposed to local hauls covering much shorter distances. These operations consisted of running two or more convoys every day, involving more than 200 mostly unarmed cargo trucks and 18-wheel tractor-trailers. By 1967 these groups were moving supplies throughout South Vietnam to sustain U.S. forces, which totaled seven divisions, six independent brigades and hundreds of company- and battalion-size units supporting the higher echelon combat formations, operating out of hundreds of cities, villages, bases, camps, supply dumps and outposts.

Of the eight motor transportation battalions that served in Vietnam, only those involved with line haul convoys, such as the 27th, 54th and 124th Transportation battalions of the 8th Transportation Group, made heavy use of gun trucks. The 6th and 7th battalions, 48th Transportation Group, did not employ gun trucks.

Each transportation battalion was made up of three to five light or medium truck companies of three platoons, with each platoon divided into two cargo squads. A light truck company had 175 men equipped with 60 2½-ton trucks, or 179 men operating 60 5-ton trucks. A medium company was serviced by about 185 men using 5-ton truck-tractors with 12- ton cargo semitrailers and 5,000-gallon fuel semitrailers. During the war 50 truck transport companies using 2½-, 5- or 12-ton vehicles operated in South Vietnam.

Line haul cargo convoys—generally 20 to 200 trucks and support vehicles, traveling through hostile territory—moved thousands of tons of materiel to combat troops and firebases daily. Such road travel was inherently hazardous. The primitive South Vietnamese road net was a patchwork affair always in a state of disrepair, with winding hairpin curves and narrow trails snaking through treacherous jungle or up steep mountain grades and over river-studded terrain—perfect ambush country.

Most ambushes were designed to harass and slow down supply units, and were rarely accompanied by infantry assaults meant to destroy a convoy. Sniper, automatic weapons and rocket-propelled grenade (RPG) fire; mines; grenades; and demolition charges were the attack methods of choice. The vast majority of these encounters were very brief—15 to 20 minutes—with the attackers attempting to knock out a few vehicles, especially ammunition and fuel carriers, then fading back into the jungle or mountainous terrain. Few ambushes were devastating, but these constant pinprick attacks wore out truck crews, damaged vehicles and effectively reduced the flow of supplies to U.S. combat units.

As the war progressed, the Americans took precautions to safeguard truck convoys. They established outposts that secured vital bridges and artillery firebases along highways to provide fire support and daily mine-clearing sweeps. They created rapid reaction forces with helicopters and ground troops prepared to quickly counterattack the enemy. In spite of these measures, and the high cost in manpower and materiel needed to implement them, Army logistic convoys remained vulnerable during the entire war. As one U.S. Army colonel in the 8th Transportation Group lamented,“The effect of attacks against our supply convoys and the resultant difficulty of running them was like trying to walk with one foot in a bucket.”

From 1965 to early 1967, Army supply columns crisscrossing South Vietnam were only thinly defended against the everyday occurrence of enemy ambushes. The first line of defense was the company truck crews themselves. M14 rifles were issued to almost all company members, and truck squad leaders toted 40mm M-79 grenade launchers and M1911A1 pistols. The company headquarters staff had two M60 machine guns; there were four per platoon (two for each squad) in a light truck company and two in each medium truck company platoon. This meager firepower allocation was at first deemed adequate based on the premise that these soft targets rarely operated beyond corps and divisional rear areas. But in Vietnam the “rear” and the “front” were indistinguishable, and truck traffic was always threatened. In this scenario, M14 rifles and M60 machine guns simply lacked the range and striking power to penetrate the thick foliage the enemy used for cover.

An initial heightened security step involved the attachment of an armed escort to the transportation units. This usually took the form of unarmored M151 quarter-ton gun jeeps mounting a single M60 machine gun, or just a driver and a passenger toting a shotgun. Further, the gun jeeps, manned by Army military police detachments, were few and not readily available for convoy duty. Assigned mainly to guard corps lines of communication, they did not consider truck escort work part of their primary function. In mid-1967, the MPs received an upgraded armored vehicle, the 73 M706 (V-100) Commando armored car. The Commandos still lacked the firepower and ruggedness to defend convoys, however, and there were never enough of them.

As the war ground on, armored infantry mechanized troops stationed in certain corps areas would lend a hand in shepherding supply convoys. As the Army strove to improve the roads in South Vietnam, travel speed increased. This was good for the truck columns, since speed was the best defense against ambushes. Ironically, this same factor left them open to attack, since mechanized units could not keep pace with them.

Through late 1967, Communist forces in South Vietnam mostly sought to harass Army supply convoys with sniper fire and by planting mines. But at that point an evolving new trend emerged that involved serious attempts by the Viet Cong and North Vietnamese Army to destroy land supply transport.

On September 2, in II Corps, a convoy from the 8th Transportation Group, shielded by only two gun jeeps, was returning from a run from Pleiku to Qui Nhon, a round trip of 200 miles. Its route—Highway 19—was a long, steep, winding mountain road bordered by open fields and heavy woods that was dubbed “Ambush Alley.” It was a longtime VC stronghold. In fact, on June 24, 1954, during the war against the French, the Viet Minh had totally destroyed a large French combat battalion along this route four miles from Pleiku—something the Americans were unaware of.

The Communist ambush, which took place a few miles west of the An Khe mountain pass and encompassed a half-mile kill zone, exploded out of the bush when the convoy was split because of mechanical problems with a fuel tanker. At dusk, the lead gun jeep and rear half of the column were attacked. The violent assault, the largest on an American convoy to date, destroyed or damaged 34 of the 39 trucks, killed seven U.S. soldiers and wounded another 17.

This stunning defeat demanded immediate and effective countermeasures. Colonel Joseph O. Bellino, commander of the 8th Transportation Group, acted on a suggestion from one of his maintenance officers to arm some of the cargo trucks with additional weapons, armor and crewmen for convoy security duty. What was to be known in the U.S. Army as the“gun truck” may have been inspired by the French during their 1945-54 Indochina War. They used World War II trucks mounting heavy .50-caliber machine guns, crewed by six men, four of whom manned the automatic weapons for ground support, perimeter defense and convoy escort.

Colonel Bellino ordered several 2½-ton trucks removed from regular service and outfitted with sandbags on the floor, driver’s cabin and sides for extra protection. Two M60 machine guns were placed in the cargo bay of each truck, and a crew consisting of a driver, two gunners and a noncommissioned officer in charge was assigned to each vehicle. Crude as it was, the gun truck, or “hardened vehicle,” was born. Amazingly, the Army top brass accepted the concept without hesitation, even though it went against established procedures that prevented any modification of vehicles and equipment without first undergoing extensive testing by the Army and the manufacturer.

Soon after the gun truck made its appearance, a suitable doctrine for its use was formulated. Referred to as the “hardened convoy concept,”the doctrine called for truck convoys to be reduced to 100 vehicles each and further subdivided into serials of 10 to 20 trucks led by a radio-equipped gun jeep and a hardened gun truck. An armored truck sporting .50-caliber M2 and 7.62mm M60 machine guns took position near the center of the column, with another radio gun jeep placed at the end of the line for command-and-control purposes. Vehicles in the convoy were spaced 100 yards apart. As the concept progressed, and on more dangerous runs, there was an average of one gun truck for every 10 task vehicles.

By late 1968, the typical truck company contained six gun trucks and seven gun jeeps, with two of the former assigned to each serial of 20 to 30 task trucks. Normally they were placed within a task-truck serial, but at times one brought up the rear. Besides providing additional firepower, the hardened convoy system gave gun trucks the ability to maneuver within the main formation in order to enforce convoy discipline and control traffic. A further advantage, and the most important one for the gun truck, lay in having the freedom to break away from the task trucks to reach the main area of engagement and fight the enemy. Once on the scene, the gun truck would halt and lay down concentrated fire. If enemy fire was light, the vehicle would maintain station and issue suppressive fire as it moved.

While traveling through ambush-prone areas, a gun jeep or gun truck often scouted up to 500 yards ahead of the convoy looking for mines, obstacles and enemy personnel. Once detected, mines were destroyed by .50-caliber machine gun fire while the truck was on the move.

When the convoy encountered light enemy fire, an alarm would go out over its radio net. The entire column would keep moving while the gun trucks returned fire. Often one or more gun trucks dropped out of formation to lay down suppressive fire to destroy or drive off the enemy. If the convoy hit heavy fire, up to six gun trucks, carrying more than 20 machine guns, rushed to the scene of the most intense action, usually arriving in less than three minutes. They would then saturate the attacker’s position with devastating retaliatory fire until he was forced to retreat.

If the opportunity arose, gun trucks might go off-road in order to close with the ambushers. Although this was an effective tactic that could easily decimate the opposition, the trucks risked hitting mines, getting stuck in holes or overturning after striking obstacles. Also, this forward movement exposed the gun truck and its crew to deadly concentrated enemy machine gun and RPG fire. After the battle, the gun trucks would rejoin the convoy, but a few might remain behind to make sure the enemy did not return or to guard any disabled vehicles until they were repaired or towed.

In very dangerous situations, gun truck crews could call in air or ground support. Coordination with the ground assets was also in the purview of the gun truck commanders.

Following the model of search-and-destroy missions, “death convoys,” composed solely of gun trucks, were routinely sent out to harass and intimidate the Viet Cong. Many of these runs were made at night to fool the opposition into thinking they were supply convoys. Once contact was established with an ambush force, the Americans would concentrate and return high volumes of murderous fire.

On Nov. 24, 1967, gun trucks got their first opportunity to prove their worth and test their tactics  in combat. As the daily convoy of 68 trucks approached Ambush Alley, a VC rifle company attacked it. RPGs struck the lead vehicle in the column, igniting a load of artillery ammunition and causing the burning wreck to block the road. Enemy soldiers then surged forward in an attempt to overrun the remaining stalled vehicles. As this was happening, the accompanying gun trucks entered the 300- yard-wide kill zone and joined the fight. Twenty minutes later, after enduring a torrent of .50-caliber and M60 machine gun fire, the VC withdrew, leaving 41 dead and four prisoners. Two U.S. soldiers were killed and 17 wounded. Five cargo carriers had been damaged or destroyed, as well as four gun trucks. In his after-action report, Colonel Bellino wrote,“The quick reaction and firepower of this convoy were the only factors that prevented this ambush from being a success.”

As if to confirm the prowess of the new gun trucks, on Dec. 4, 1967, a 77- vehicle convoy from the 8th Transportation Group was hit by an enemy infantry company using heavy machine guns and mines. After a 30-minute encounter with the convoy’s six gun trucks, the VC lost 13 killed and one captured, while the Americans suffered one killed and six wounded, and several of their trucks were damaged.

Although never officially authorized or fully integrated into the Army’s transportation doctrine, gun trucks were a great economy of force in protecting truck traffic in Vietnam, thus relieving military police and combat units from that responsibility. Their success in helping supply convoys make their deliveries was a testament to American servicemen’s ingenuity and adaptability to changing combat conditions.

 

Originally published in the December 2013 issue of Vietnam. To subscribe, click here.