Leonardo da Vinci designed an armored tank with sloping protective plates and multiple guns.
His fighting-vehicle drawing dates from the late 1480s and was probably prepared for Ludovico Sforza, the ruler of Milan. The vehicle has a conical, turtle-like shell made from heavy plates and a circular arrangement of cannons around its lower edge. A crew inside would theoretically turn cranks connected to the wheels.
The sloping armor was useful in concept because angled surfaces could deflect incoming projectiles more effectively than flat vertical surfaces. However, the design had serious practical problems. Its weight would have made movement difficult, and one famous reconstruction identified a possible gearing error that would cause the wheels to turn in opposite directions. Some historians think the apparent flaw may have been deliberate to keep the design secret.
Leonardo’s vehicle was not a modern tank, which requires an engine, tracks, and a protected fighting compartment. It is better understood as an early armored fighting-vehicle concept.