Leonardo da Vinci sketched an armored tank as a conical, cannon-covered military vehicle.
The design appears in Leonardo’s studies for Ludovico Sforza, Duke of Milan, around 1487–1489. Its sloping shell was inspired partly by a tortoise’s protective form. Small cannons projected through openings around the vehicle, allowing occupants to fire while shielded by armor.
The proposed machine was meant to move using cranks connected to wheels. Several men inside would turn the cranks, while the armored covering protected them from enemy fire. The vehicle was therefore a mobile weapons platform, not a modern tank with an engine, turret, and tracks.
A famous detail in the drawing is that some gears appear to work in the wrong direction. Historians disagree about whether this was a deliberate security flaw, a copying mistake, or simply an error. In any case, the sketch was never known to have been built or used in battle.