Leonardo da Vinci’s proposed armored fighting vehicle is commonly called Leonardo’s tank.
Leonardo drew the vehicle in the 1480s while working for Ludovico Sforza in Milan. Its conical, turtle-like shell was intended to protect soldiers inside, while cannons projected through openings around the perimeter. The vehicle was to move through hand-operated cranks connected to wheels.
The design was never built in Leonardo’s lifetime. Modern reconstructions have demonstrated that the surviving drawing presents a practical difficulty: the gearing, as shown, would make the wheels turn in opposite directions. Some historians think this may have been a deliberate error to prevent unauthorized use, while others regard it as a design mistake or an artifact of the drawing.
Calling it a “tank” is convenient but anachronistic. The modern military term became established centuries later, especially during the First World War. Leonardo’s vehicle was an early armored-war-machine concept, not a petrol-powered tracked tank.