What Leonardo da Vinci military vehicle design is often called the Leonardo tank?

Leonardo da Vinci's famous armored military vehicle design is often called the Leonardo tank.

Leonardo designed the fighting vehicle around 1487 for Ludovico Sforza, the Duke of Milan. The machine had a conical armored shell resembling a tortoise and was intended to carry guns around its perimeter. Crews would turn internal cranks connected to wheels, allowing the vehicle to move across a battlefield while protecting its occupants.

The design was never built in Leonardo's lifetime. A commonly repeated story says that its gears were intentionally arranged backward to prevent the Duke from using the machine, but historians disagree about whether this was deliberate sabotage, a drawing error, or an unresolved engineering issue.

Calling it a tank is convenient but anachronistic: the modern tank emerged during the First World War. Leonardo's vehicle was an armored fighting machine, not a tested tracked tank.