In late 1944 the Germans completed the first Panzerkampfwagen VIII Maus the heaviest fully enclosed armored fighting vehicle ever to see the light of day. Just two hulls and one turret were completed before fully enclosed armored fighting vehicle ever built captured the testing grounds.
The completed Maus was 33 ft 6 inches long, 12 ft 2 inches wide, 11.9 ft high and had a weight of 188 metric tons. The Maus’s main gun was a Krupp-designed 128 mm gun.which was powerful enough to destroy all Allied armored fighting vehicles in service at that time, some at ranges beyond 3,800 yards.
The major issue with the Maus design was to develop an engine and drive train which would be able to propel the tank but would still be able to fit inside the tank. Eventually, they engineers came up with a 44 litre engine and an electrical drive train which provided a maximum speed of 12 mph.
Because the weight of the Maus would mean it would collapse any bridge it tried to cross the plan was to have it ford through all rivers thus it could cross to a depth of 6 ft 7 in or submerge up to a depth of 26 ft and use a snorkel. The time it took to get anywhere would be very long indeed.
Five were ordered, but as stated before only two hulls and one turret were completed before the advancing Allies found them.