Leonardo da Vinci’s armored fighting vehicle is commonly described as an early tank.
Leonardo designed the vehicle in the 1480s for Ludovico Sforza, the ruler of Milan. The machine had a conical armored shell inspired partly by a tortoise. It was intended to protect soldiers while carrying several light cannons around its perimeter.
The vehicle was to move using cranks connected to wheels. However, the surviving design contains a gear arrangement that would make the machine move backward if built exactly as drawn. Historians debate whether this was an intentional secret flaw, a drawing error, or an unfinished design detail.
Leonardo’s vehicle was never used in battle and was not a tank in the modern technical sense. Modern tanks developed centuries later, especially during World War I. The comparison is based on its combination of armor, mobility, and mounted weapons.