In Leonardo da Vinci's military designs, what vehicle is known as the Leonardo tank?

The vehicle known as the Leonardo tank was an armored fighting vehicle.

Leonardo designed this conical, covered vehicle in the late fifteenth century, probably for military patron Ludovico Sforza. Its sloping shell was intended to deflect enemy fire, while cannon were arranged around the platform so the crew could fire in several directions.

The vehicle was meant to be moved by people turning internal cranks connected to wheels. A famous drawing appears to show a gearing problem that would make the vehicle move backward. Historians debate whether that error was accidental or deliberate, since Leonardo may have wanted to conceal military ideas from unauthorized readers.

It was never built as a fifteenth-century battlefield machine. Calling it a tank is a modern comparison: the design resembles a tank in its armor and all-terrain military role, but it had no engine, turret, or modern armored-vehicle technology.