What armored military vehicle did Leonardo da Vinci design with a conical shell and cannons?

Leonardo da Vinci designed a fighting vehicle with a conical armored shell and cannons.

The vehicle resembles a low, covered platform or tank. Its sloping armor was intended to deflect enemy fire, while a ring of light cannons allowed crew members to fire in different directions. Inside, soldiers would turn cranks connected to wheels to move the machine.

Leonardo drew the design around 1487 for the court of Ludovico Sforza in Milan. It was never built for Renaissance warfare, and the proposed mechanism has a serious practical problem: the wheel arrangement as drawn would make the vehicle difficult or impossible to drive correctly. Some historians think that this may have been an intentional error to keep the design secret.

The vehicle is often called Leonardo’s tank, but “fighting vehicle” is a more historically cautious name. Modern tanks emerged much later and use engines, tracks, and armor systems unlike Leonardo’s hand-powered concept.