The Tortoise, An Unknown WW2 Heavy Tank – Video from The Tank Museum

The Heavy Assault Tank or Assault Gun, Tortoise, was a British tank design developed in World War II but never put into mass production. It was developed for the task of clearing heavily fortified areas and as a result favoured armour protection over mobility.
In the early part of 1943, the Allied forces anticipated considerable resistance in the projected future invasion of Europe, with the enemy fighting from heavily fortified positions such as the Siegfried Line. As a result, a new class of vehicles emerged, in the shape of Assault tanks, which placed maximum armour protection at a higher priority than mobility.