The Panzer Landstampfer P. 9000 Lama was by far the largest tank ever built. Weighing 8950 tons and measuring 70 meters in length, the behemoth was to have been the crown jewel of the German army. Thankfully several flaws prevented its use in war:
It was impossible to repair in the field, as even a single tread plate weighed as much as a common tank.
The tank was too heavy to travel on most terrain. It sank in swamps, crushed any road it traveled, and was unable to move efficiently on anything but solid granite. Oddly enough, it could float without difficulty.
Despite its size, the tank was relatively weak. Its massive engine required a thermal exhaust port so wide that a smaller tank would have been able to travel down its meridian trench and fire into the engine itself, causing a chain reaction that could destroy the entire tank.
The tank required a crew of 78 men to operate, and featured internal dormitories to house them. Unfortunately, a design flaw left it with only one functional bathroom. The results were the last nail in the coffin: Within its first day of prototype trials, the toilet became clogged and sewage slowly backed up, flooding the lower 3 decks. Command quickly arranged for a compliment of “scheißeschlepper” tanks to pump and remove the offending material, but the damage was done when Heinz Guderian declared the tank’s element of surprise would be ruined when opposing troops smelled it coming.
Additionally, the cannon was so large that were it ever fired, it would drive the entire tank 50ft into rock solid ground and cause an earthquake that would have annihilated most of Europe.
The only working prototype of the tank was literally scrapped, and its metal was used to build the entire Berlin, Munich and Hamburg subway systems. But the story doesn’t end there. In 2016, historians uncovered plans for the Panzer XXVI Walross, a 250,000 ton tank the size of an entire city, which would have traveled on treads five miles long and fired hydrogen bombs from its 4,000mm cannon.
It was cancelled, apparently, because it would’ve required more metal than exists in the entire solar system.