Leonardo da Vinci designed an armored fighting vehicle commonly known as a tank.
His late-15th-century design resembled a covered, conical platform with openings for cannons. It was intended to move across a battlefield while protecting the crew and allowing weapons to fire outward. The vehicle would have been propelled by people turning internal cranks connected to wheels.
Leonardo’s surviving drawing contains a famous mechanical problem: the gear arrangement appears to make the vehicle move backward. Some historians think this may have been an intentional flaw to prevent the design from being used, while others regard it as an error or an issue in interpreting the sketch.
The vehicle was never built for Renaissance warfare. Its resemblance to a modern tank is retrospective, since tracked engines and armored military vehicles developed centuries later.