Leonardo da Vinci designed an armored tank, a conical fighting vehicle driven by teams of men inside.
The design appears in Leonardo's papers from the late 15th century, probably produced while he sought employment with Ludovico Sforza in Milan. Its sloped, conical shell was intended to deflect incoming projectiles, and the vehicle carried several light cannons around its perimeter. Internal operators would turn cranks connected to wheels to move it across the battlefield.
The surviving drawing includes a famous mechanical problem: the gearing, as sketched, would make the wheels turn in opposite directions. Historians debate whether this was an error, a deliberate sabotage feature, or an unfinished design. In any case, no evidence shows that the machine was built for Renaissance warfare.
The vehicle is commonly called Leonardo's tank, but it was not a modern engine-powered tank. It had no combustion engine, and its proposed power came from human operators.