Panzer VIII Maus
Panzerkampfwagen VIII Maus ("Mouse") was a German World War II super-heavy tank completed in late 1944. It is the heaviest fully enclosed armoured fighting vehicle ever built. Five were ordered, but only two hulls and one turret were completed before the testing grounds were captured by advancing Soviet military forces.
History of the tank
Although an experimental 15-ton tank, the M1924, reached the mock-up stage, this and other attempts to satisfy War Department and infantry specifications proved to be unsatisfactory. In reality it was simply impossible to build a 15-ton vehicle meeting both War Department and infantry requirements.