What name is commonly given to Leonardo da Vinci's armored, cone-shaped military vehicle?

Leonardo's tank is the common name for his armored, cone-shaped fighting vehicle design.

Leonardo drew the vehicle in the 1480s, probably while seeking military patronage from Ludovico Sforza, ruler of Milan. The design resembled a covered, circular platform with sloping armor and multiple gun openings. It was intended to move across a battlefield while protecting the soldiers inside.

The machine was never built in Leonardo's lifetime. Its propulsion system appears to contain a famous technical problem: the internal cranks, as drawn, would make the wheels turn in opposite directions. Some historians think this may have been an intentional error to keep the design from being used by others, although that explanation cannot be proved.

Calling it a tank is modern shorthand. Leonardo did not use the twentieth-century military term, and his design was not a modern tracked tank. It was a proposed armored fighting vehicle powered by people turning cranks.