Leonardo da Vinci sketched an armored tank, a conical military vehicle with cannon openings.
His fighting vehicle was designed in the late fifteenth century as a protected platform that could move across a battlefield and fire weapons through openings in its armor. The sloping, conical shell was intended to deflect incoming projectiles, while the interior arrangement suggested human-powered wheels and multiple guns.
The vehicle was never built for Leonardo's patrons or used in battle. Some modern reconstructions identify a gearing problem in the famous drawing: the wheels appear arranged so that the machine could not move correctly without modification. Whether that was deliberate concealment or an error remains debated.
Although often called a tank, Leonardo's vehicle was not an engine-powered modern tank. It was a proposed armored fighting machine from the Renaissance.