The basic design was ordered by the Waffenamt as a parallel development to the Porsche Maus in June 1943. It was the heaviest of the Entwicklung (E) series of vehicles, meant to standardize as many components as possible.
In November 1942, Krupp suggested a design weighing 155 tons, compared to the 188 tons of the Maus - but still using the Maus turret. In December 1942, Krupp suggested a design weighing 130 tons which used many of the same components as the Tiger tank with Maus turret — referred to as the "Tiger-Maus". Weight savings were to be from thinner armour, and narrowing and shortening the vehicle.
British forces captured the prototype in 1945, shown here on a trailer.
After 1944, work continued at a very slow pace until canceled in favour of the Maus.
The prototype had a HL230P30 engine due to the lack of HL234 units from Maybach. The HL230 was the same engine that was used on the King Tiger and Panther tanks. It was suitable for the 45-tonne Panther, underpowered for the 70-tonne King Tiger, and grossly under-powered for a 140-tonne design. The prototype would have been fitted with the 15 cm Kwk44 gun, though the final selection between the 15 cm Kwk44 and the 17 cm Kwk44 had not been made. The hull had sloped armor, typical of post-1943 design. Wheels were overlapped, similar to the King Tiger and Panther.
The first prototype was never completed and was found by allied forces on the factory floor in 1945. The partially completed vehicle was removed by the British Army for evaluation and then scrapped.