The Panzer VI was a Heavy Tank used by Blue Germany in the early 1940's.
While the Panzer V was in design, intended to replace both the Panzer III and Panzer IV, the Blue German High Command observed the development of tanks in Fascist France. In particular, the performance of French tanks against British anti-tank guns during the Invasion of England in 1940 worried the German army, who drew up a requirement for a tank heavier than the 20-ton Panzer V. Several companies began to work on the design of a new Heavy Tank in the 30-ton range.
While the French had much heavier tanks than the Germans during this time, including the Char 2C, the German High Command wished to keep the weight of the tank as low as possible to fit in with their concept of mobile warfare. This meant that several larger concepts, including the VK 45 and VK 65, were rejected for production in 1941. Only designs in the 30 ton range would be considered for immediate production.
Several companies submitted designs, including Henschel and Porsche. Henschel's original design, the VK 30.01(H), was thought to be obsolescent and was not accepted, mostly due to its inability to accept the larger armament that the Waffenamt was then demanding. Porsche's design team quickly redesigned their tank to accommodate an 88mm gun, based off the Flak 18 anti-aircraft gun. It was on this basis that the design was accepted for production; the Henschel team began redesigning their chassis to accept a more powerful gun, and their design would become the VK 36.01(H).
While the original specification called for a tank of 30 tons, the VK 30.01(P), the Porsche project, had grown greatly to more than 45 tons. This was due to its need to take the larger gun and, therefore, a larger turret. The final weight of the tank would be nearly 47 tons, but it was nonetheless adopted for production.
Testing of the prototype showed that the innovative Porsche electric-drive transmission provided a smooth final drive to the tank, which was felt to be desirable.