Bridge and Churchill Crocodile flame-throwing tank in 1945 It was in the
World War II era that the importance of armoured bridge layers, as well as
combat engineering vehicles and
armoured recovery vehicles, became fully clear. With the advent of
Blitzkrieg warfare, whole divisions had to advance along with tanks, which were suddenly far out-pacing the speed of infantry soldiers. Besides leading to the advent of
self-propelled artillery/
assault guns,
mobile anti-aircraft and
armoured personnel carriers/
cars, it became clear that functions like vehicle repair, mine-clearing, and the like would have to be carried out by armoured vehicles advancing along with tanks. These forces would have to be able to cross all forms of terrain without losing speed, and without having to concentrate their thrusts over certain bridges. The rising weight of armoured vehicles meant that fewer bridges could support these massed crossings. The only feasible solution to the dilemma posed by the mobility of all-mechanised armed forces was a dedicated platform that could improvise river and obstacle crossings at short notice and in inconvenient locations. Tracked and armoured, it was capable of operating alongside combat units, crossing rough terrain and advancing in the face of light fire. To maximize on common parts and ease maintenance complications, they were usually based on existing tank chassis. One of the earliest series-produced examples is the
Brückenleger IV, a German AVLB based on the
Panzer IV, which entered service with the
Wehrmacht in 1940. Twenty were built, but problems of excessive weight limited the vehicle's effectiveness, and eventually all 20 were converted back to tanks. A second type was a infantry assault ladder on Panzer IV chassis of which only two were built. A new scissors bridge design was brought out by the British in response to the war, sufficient to support a 24-ton load over . This was developed for the
Covenanter tank. It developed into a 30-ton capacity and was carried by a turretless
Valentine tank. It was used in Italy, North West Europe and
Burma. The
Allies developed similar equipment, mostly based on the ubiquitous
Churchill infantry tank carrying the
Small Box Girder, and the
Sherman medium tank of the
British and
U.S. armies, respectively. In some early designs, bridge-layers could emplace bridges, but not retract them. Other vehicles were integral to the bridge themselves, such as the
Churchill Ark, wading to the middle of a river or driving up against an obstacle and extending simple ramps in both directions. Following vehicles would drive directly over the bridge layer. ==Modern==