What Leonardo da Vinci invention was an armored vehicle powered by crews turning cranks?

Leonardo da Vinci designed an armored vehicle powered by crews turning cranks. His late-15th-century concept resembles a conical tank covered with metal plates and carrying several light cannons.

The sloped outer shell was intended to deflect incoming projectiles. Inside, operators would turn cranks connected to wheels, allowing the vehicle to move across the battlefield. The design included openings for guns around the vehicle’s broad circumference.

A famous drawing appears to show a flaw: the gearing would make the vehicle move backward rather than forward if built exactly as sketched. Historians debate whether this was an error, an intentional sabotage feature, or simply an unfinished design.

Leonardo’s vehicle was never built or used in warfare during his lifetime. Calling it a tank is useful as a modern comparison, but it did not have an engine, rotating turret, or enclosed crew compartment like later tanks. Its historical importance is as an early concept for protected mobile artillery.