Leonardo da Vinci’s proposed armored fighting vehicle is commonly called a tank.
Leonardo designed the vehicle in the late 15th century, probably around 1487, while working for Ludovico Sforza in Milan. Its conical, turtle-like shell was intended to protect soldiers inside while they operated a set of wheels and gears.
The design included openings for cannons around the vehicle’s sloping outer shell. Leonardo’s drawings show a crew turning cranks to drive the wheels, although the gearing as usually illustrated would make the vehicle unable to move forward. Historians often suggest that this may have been a deliberate error to prevent the design from being copied.
It was never built or used in a Renaissance battle. The word “tank” was not used for it in Leonardo’s time; the modern label comes from its resemblance to later armored tanks. It is therefore best understood as an early concept for an armored fighting vehicle, not a working tank.