Leonardo da Vinci designed an armored tank-like fighting vehicle with sloping plates and multiple cannons.
The vehicle appears in drawings from about 1487–1489, probably made while Leonardo was working for Ludovico Sforza in Milan. Its conical covering resembles a tortoise shell and was intended to protect soldiers inside. Several light cannons project through openings around the vehicle.
The proposed machine was powered by internal cranks connected to wheels. Some modern commentators note that the crank arrangement would make the vehicle difficult or impossible to drive as drawn, possibly because of a deliberate design error or a drafting mistake. It was never built for Renaissance warfare.