Leonardo da Vinci’s armored fighting vehicle design is commonly called Leonardo’s tank.
Leonardo sketched the vehicle around 1487–1490 while working in Milan for Ludovico Sforza. Its body was a conical, turtle-like shell made from wooden plates reinforced with metal. The sloping surface was intended to deflect enemy fire, and the design included several light cannons around its perimeter.
The vehicle was to be moved by people turning cranks connected to wheels. Leonardo’s drawing appears to contain a mechanical error: the internal gears would make the wheels turn in opposite directions. Historians debate whether that was accidental, deliberate concealment, or simply an unfinished design.
It was never built in Leonardo’s lifetime, so “tank” is a modern descriptive name rather than a term he used. The concept is also not a modern armored tank in the technological sense: it had no engine, suspension, or rotating turret. Modern reconstructions show that the basic idea can be made workable after correcting the gearing.