Leonardo da Vinci sketched an armored tank with a conical shell and internal gears.
His 1485 design shows a covered, turtle-shaped vehicle fitted with sloping armor. Several people inside were intended to turn cranks connected to wheels, allowing the machine to move across the battlefield. The sloped shell could help deflect incoming projectiles, while openings around the sides allowed weapons to fire outward.
The vehicle is commonly called Leonardo’s tank, although Leonardo himself described it as a covered fighting machine rather than using the modern word tank. The drawing also contains a famous mechanical problem: the gear arrangement appears to make the wheels turn in opposing directions. Some historians think this was deliberate, perhaps to keep the idea secret, while others regard it as a design error.
No evidence shows that Leonardo built the vehicle. It belongs to his large group of military engineering projects, which included bridges, artillery concepts, and fortification studies. The design is therefore best understood as a Renaissance concept for armored mobility, not as an operational tank.