Leonardo da Vinci designed a tank as a four-wheeled armored vehicle powered by cranks.
His fighting vehicle, drawn in the 1480s, had a conical cover inspired partly by a tortoise shell. Sloping armor was intended to deflect projectiles, while several light cannons projected through openings around the vehicle. The crew would turn cranks connected to the wheels to move it.
The design was never built or used in battle during Leonardo’s lifetime. A commonly repeated story says that a deliberate error in the gearing made the machine impossible to operate and was intended to conceal the design. That claim is uncertain, and the drawing itself presents practical problems, including the inward-facing arrangement of the cranks.
Modern writers call it Leonardo’s tank, but it was not a modern tracked tank. It was a proposed armored fighting vehicle, and its wheels and hand-powered mechanism limited its likely battlefield usefulness.