Leonardo da Vinci sketched an armored tank as a covered military vehicle for battlefield transport and attack.
His fighting vehicle had a conical cover inspired by a tortoise shell. Sloping armor was intended to deflect incoming projectiles, while a group of small cannons projected through openings around the vehicle. The machine was designed to move on wheels turned by people operating internal cranks.
The vehicle is commonly called Leonardo's tank, although it was not a modern tank. It had no engine, tracks, or established method of steering, and some reconstructions suggest that the original mechanism may not have worked as drawn. One famous interpretation says Leonardo deliberately inserted a mechanical flaw to prevent immediate military use, but that claim is debated rather than proven.
The concept is distinct from Leonardo's humanoid mechanical knight. The fighting vehicle is a low, armored platform carrying weapons, whereas the mechanical knight was designed as a human-shaped automaton.