Leonardo da Vinci sketched an armored tank as a conical military vehicle carrying many small cannons.
His famous fighting-vehicle design appears in a notebook from the late 15th century. It resembles a covered, turtle-shaped platform with sloping armor intended to deflect projectiles. A ring of light cannons was arranged around the vehicle so that it could fire in several directions.
The vehicle was supposed to move through the coordinated effort of people turning internal cranks. Some modern commentators point out that a commonly built reconstruction has a gearing problem that would prevent its wheels from turning in the intended direction. Historians debate whether that feature was an error, a deliberate safeguard, or an unfinished design.
Leonardo’s vehicle was never used in battle. It is called an armored tank because its protected body and mobile artillery anticipate features associated with later tanks, but it lacked an engine, tracks, and a practical battlefield testing history.