What kind of military vehicle did Leonardo da Vinci design with sloping armor and cannons?

Leonardo da Vinci designed an armored fighting vehicle with sloping armor and multiple cannons. The machine appears in drawings from the late 15th century and is often described as an early ancestor of the modern tank.

The vehicle has a conical, turtle-like shell made from wooden plates reinforced with metal. Cannons project through openings around its perimeter, allowing it to fire in several directions while protecting the crew inside. Leonardo also included a system of gears and wheels intended to move the vehicle.

The design was probably never built in Leonardo’s time. Historians have noted that the mechanism shown in the drawing would not work as presented because of a likely gearing problem or deliberate concealment of the design. A corrected model can move when its gearing is altered.

Calling it a tank is useful as a comparison, but Leonardo’s vehicle was a battlefield concept rather than a functioning armored vehicle. It had no engine and depended on human power.