Leonardo da Vinci’s armoured tank was a circular military vehicle intended to move over a battlefield.
Leonardo drew the fighting vehicle in the late fifteenth century, probably while seeking patronage from Ludovico Sforza, the Duke of Milan. Its conical cover was inspired partly by a tortoise shell and was fitted with multiple light cannons around the perimeter. The crew would operate internal cranks connected to the wheels.
The machine was never built for Leonardo’s armies. The surviving design contains a famous mechanical problem: if the proposed gears were arranged exactly as drawn, the wheels would turn in opposite directions. Some historians interpret this as an intentional error to prevent others from using the design, while others regard it as a drafting mistake.
Modern replicas often correct the gearing and use the design as an educational example. Leonardo’s vehicle was not a modern tank, but its armour, enclosed crew compartment, and mobile guns anticipated several features associated with later armoured fighting vehicles.