Type 4 tank

The Type 4 tank, known as the "Bathtub" was a Sierran tank produced in 1918 and 1919. The bathtub tank was essentially tank treads with a domed armored shell body, looking like an upturned bathtub. In its day it was termed a heavy tank but is essentially comparable to a medium tank.

Development
The Type 4 was developed between April and September 1918, with the Sierran Army looking. The first prototype was made from 1/2 inch steel on the top and sides and 1 inch steel on the front, making it much too heavy to be effective. Indeed in trials, the two Gerald engines used could only propel it to around 4 mph on the flat ground, with the tank unable to climb an 8 degree slope.

Production and service history
The armor was then made much lighter and no machine guns were added to the final model, which entered production in August 1918. Keen to show off this impressive model, production was rushed and two were shipped over to Europe in time for the Fifth Battle of Ypres in late September. The sight of the bathtubs on the battlefield were very impressive; a German officer's diary reports a large iron sausage-shaped tank easily dispersing his men (...Es sah aus wie eine Wurst, hatte die Farbe einer Wurst und verjagte meine Soldaten). But, they were still cumbersome, slow and ungainly and repeated mechanical failures saw one fall apart and the second had steering failures and crashed into a house.

By 1918, six tanks had been completed and the remaining parts were used to make 3 additional models. By 1920, though, the further need for a tank corps was questioned by government and parliament cut off most funding for the tank corps, which led the military to store away the seven remaining Type 4s, all of which were sold for scrap in 1925.