What type of vehicle did Leonardo da Vinci design with sloping armor and cannon?

Leonardo da Vinci designed an armored tank-like fighting vehicle with sloping armor and cannon.

He drew the vehicle in about 1487–1489 while working on military-engineering ideas for Ludovico Sforza, ruler of Milan. The circular, covered platform was fitted with multiple light cannons aimed through openings in its armor. Sloped plates were intended to deflect incoming projectiles.

The vehicle is often called Leonardo’s fighting vehicle or Leonardo’s tank, although the word “tank” belongs to much later military history. It was designed for a crew inside the armored shell and was moved by internal cranks connected to wheels.

A famous drawing error makes the design appear mechanically unable to move: some reconstructions interpret the gears as reversed. Historians debate whether this was deliberate secrecy or simply an error. Leonardo’s surviving sketch proves the concept, not that a working prototype was built.