What did Leonardo da Vinci design as a covered, wheeled fighting machine resembling a modern tank?

Leonardo da Vinci designed an armored fighting vehicle resembling a modern tank.

Leonardo sketched the machine around 1487–1489 while working in Milan for Ludovico Sforza. Its conical cover was intended to protect soldiers, while guns placed around the lower edge could fire in several directions. The design used sloping armor, which would help deflect incoming projectiles.

The vehicle was powered by hand-operated cranks connected to wheels. It was not built in Leonardo’s lifetime, and a famous drawing appears to contain a gear arrangement that would prevent the vehicle from moving as drawn. Historians debate whether this was an error, a deliberate safeguard, or a sign that the design remained incomplete. It is often called a tank, but it was not an operational tank in the modern military sense. The first tanks used in warfare appeared during World War I, more than four centuries later.