Leonardo da Vinci designed an armored vehicle with sloped plating and internal hand cranks called a tank.
Leonardo's fighting vehicle appears in sketches from the late fifteenth century. Its conical, turtle-like cover was intended to deflect incoming projectiles, while wheels driven by people inside would move the vehicle across the battlefield. The design also included multiple light cannons arranged around the lower edge, giving it the appearance of a mobile armored platform.
The vehicle was never built for Leonardo's patron, Ludovico Sforza, and it was not a practical modern tank. The proposed gearing has a well-known problem: as usually drawn, the wheels would turn in opposite directions. Some writers interpret that as an error; others suggest Leonardo may have deliberately inserted it to prevent unauthorized construction.
Modern tanks use engines, tracks, armor, turrets, and sophisticated targeting systems. Leonardo's machine had none of those later features, but its combination of armor, mobility, and weapons makes it an important early armored-vehicle concept.