An extract on #boho
The British Gun Carrier Mark I was the first Self-propelled artillery and was fielded in 1917. It was based on the first tank, the British Mark I and carried a heavy field gun. The next major advance was the Birch gun developed for the motorised warfare experimental brigade (the Experimental Mechanized Force). This mounted a field gun, capable of the usual artillery trajectories, on a tank style chassis.
During WWII, most nations developed self-propelled artillery vehicles. These had mounted guns on a tracked chassis (often that of an obsolete or superseded tank) and provide an armoured superstructure to protect the gun and its crew. The first British design, "Bishop", carried the 25 pdr gun-howitzer, but in a mounting that severely limited the gun's performance. It was replaced by the more effective Sexton. The Germans created many examples of lightly armored self-propelled anti-tank guns using captured French equipment (example Marder I), their own obsolete light tank chassis (Marder II), or ex-Czech chassis (Marder III). These led to better protected tank destroyers, built on medium tank chassis such as the Jagdpanzer IV and Jagdpanther.
A flame tank is an otherwise-standard tank equipped with a flamethrower, most commonly used to supplement combined arms attacks against fortifications, confined spaces, or other obstacles. The type only reached significant use in the Second World War, during which the United States, Soviet Union, Germany, Italy, Japan and the United Kingdom (including members of the British Commonwealth) all produced flamethrower-equipped tanks. Usually, the flame projector replaced one of the tank's machineguns, however, some flame projectors replaced the tank's main gun. Fuel for the flame weapon was generally carried inside the tank, although a few designs mounted the fuel externally, such as the armoured trailer used on the Churchill Crocodile.
Flame tanks have been superseded by thermobaric weapons such as the Russian TOS-1.
An internal security vehicle (ISV), also known as an armoured security vehicle (ASV), is a combat vehicle used for supporting contingency operations. Security vehicles are typically armed with a turreted heavy machine gun and auxiliary medium machine gun. The vehicle is designed to minimize firepower dead space and the vehicles weapons can be depressed to a maximum of 12. Non-lethal water cannons and tear gas cannons can provide suppressive fire in lieu of unnecessary deadly fire.
The vehicle must be protected against weapons typical of riots. Protection from incendiary devices is achieved though coverage of the air intake and exhaust ports as well as a strong locking mechanism on the fuel opening. Turret and door locks prevent access to the interior of the vehicle by rioters. Vision blocks, ballistic glass and window shutters and outside surveillance cameras allow protected observation from within the vehicle. Wheeled 4x4 and 6x6 configurations are typical of security vehicles. Tracked security vehicles are often cumbersome and leave negative political connotations for being perceived as an imperial invading force.