What defensive Leonardo da Vinci design is commonly called the Leonardo tank?

Leonardo da Vinci’s armoured tank was a conical, covered fighting vehicle designed for battlefield use.

Leonardo sketched the fighting vehicle in the 1480s while seeking military commissions. Its sloping shell was intended to deflect projectiles, and the design included multiple light cannons arranged around the platform so that it could fire in several directions.

The vehicle was meant to be moved by people turning cranks connected to gears and wheels. A commonly repeated story says Leonardo deliberately inserted a gear flaw to prevent the design from being built, but historians debate the significance of the apparent mismatch and whether it was simply an error in the drawing.

The tank was never constructed in Leonardo’s lifetime. It is therefore best understood as a conceptual armoured fighting vehicle, not a working predecessor of the powered tanks used in the twentieth century.