Gun truck

A gun truck is an armored vehicle with one or more crew-served weapons, typically based on a military truck. Gun trucks often have improvised vehicle armor, such as scrap metal, concrete, gravel, or sandbags, which is added to a heavy truck.

When the prospect of a German invasion of Britain seemed likely, the British Army designed and built an improvised armored vehicle, the Bedford OXA. It was based on the one and a half-ton OXD truck and was upgraded with armor plate, and armed with a .55 in anti-tank rifle and a Bren gun. Slightly less than a thousand were built by 1941, and they were employed by the British Home Guard.

Other British examples from the invasion-scare period were the Armadillo armoured fighting vehicle and the Bison concrete armoured lorries. Both were conventional trucks fitted with improvised armour, in the case of the Bison, a concrete fighting-compartment was carried, essentially making a mobile pillbox. The Armadillo used two walls of wood, with the space between filled with gravel. Both vehicles had poor mobility and were employed for airfield defense by the Royal Air Force. In the event of a surprise, airborne attack, Bisons would deploy a short distance from the key points of the airfield and probably fight from static positions, positions where fixed defenses often could not be constructed as they would impede aircraft movement during day–to–day operations. The Armadillo's mobility, while poor, was better than the Bison's and it was intended they would take on a mobile role similar to a conventional armoured vehicle.

During the war in North Africa all contenders made extensive use of portees and gun trucks. In particular, the Italians adapted and used seven gun trucks based on heavy trucks Fiat 634 and equipped with an 102/35 su Fiat 634N anti-aircraft gun in 1941-1942; initially intended for anti-ship and anti-air defense, they proved to be very effective against British tanks. Another sixteen gun trucks, still between 1941 and 1942, were based on heavy trucks Lancia 3Ro mounting a 100/17 with full rotation in the back. In 1942 the 90/53 on Lancia 3Ro entered service, still based on the same truck as the previous one, but equipped with the excellent Cannone da 90/53, dual role high velocity gun; 30 were produced in 1942, another 90 were built on a different chassis as 90/53 on Breda 52. The 75/27 CK on Ceirano 50 CMA was instead already produced during the late 1920s to provide anti-aircraft support to the divisions, but by 1939 it was completely outdated, both in terms of mobility and firepower. In general these gun trucks proved to be quicker to position and open fire than normal artillery and they were valid if well hidden and protected, but the excessive height and mediocre mobility always remained major limitations. Numerous normal trucks such as the SPA Dovunque 35, the Fiat-SPA 38R and the SPA AS.37 were equipped with an autocannon Breda 20/65 mod.35 for the protection of convoys. Likewise, many captured enemy vehicles, for example the Ford F15A, were equipped with the same weapon. Another English vehicle, the light truck Morris CS8, was equipped with a 65/17 howitzer, about 30 were fitted. There were then numerous vehicles equipped with the 47/32 gun: the scout vehicles SPA-Viberti AS.42, the Fiat-SPA AS43 and the light truck SPA AS.37.

During the Vietnam War, it was the mission of the US Army Transportation Corps to ferry supplies from the coastal ports of Qui Nhon and Cam Ranh Bay to inland bases located at Bong Son, An Khe, Pleiku, Da Lat and Buon Ma Thuot. The logistical requirements of the MACV were huge, and 200-truck convoys were not uncommon. These convoys were tempting targets for Vietcong (VC) guerrilla groups, who often sprung ambushes in remote areas.

One unit that often fell victim to such attacks was the 8th Transportation Group, based in Qui Nhon. Two dangerous stretches of Route 19 between Qui Nhon and Pleiku became the VC's favorite kill zones, the "Devil's Hairpin" in An Khe Pass and "Ambush Alley" below Mang Yang Pass as incidents occurred there on an almost daily basis.

Providing security for convoys proved virtually impossible, as the Military Police units whose task it was did not have the manpower or equipment to secure the whole highway. Other military combat units only controlled the stretch of road within their designated checkpoints and could serve as a reaction force; so for much of the way, it fell onto the transport units to provide themselves immediate security. At first, they did this with armed jeeps, but these rapidly proved inadequate in the face of improved VC and North Vietnamese People's Army of Vietnam weaponry and tactics.

On September 2, 1967, a particularly devastating attack killed seven drivers, wounded 17 and destroyed or damaged 30 trucks. To remedy the obvious vulnerability of the supply convoys, a "hardened convoy" concept was implemented, protected by a new type of security vehicle. This gun truck, as it became known, was based on the two-and-a-half-ton cargo truck, protected by a barrier of sandbags, and armed with two M60 machine guns. Hardened convoys were smaller than previously, being composed of only 100 trucks, and their security detail was increased until there was one gun truck for every 10 transport trucks.