Which Leonardo da Vinci design is often described as an early tank?

Leonardo da Vinci’s armored vehicle design is often described as an early tank.

Leonardo sketched the fighting vehicle in the late fifteenth century, probably while seeking military employment from Ludovico Sforza, the Duke of Milan. The machine had a conical, armored shell intended to protect occupants from enemy fire. Small cannon were arranged around the platform so the vehicle could threaten targets in several directions.

The vehicle was designed to be moved by people turning cranks connected to wheels. A famous drawing appears to contain a gear arrangement that would make the machine move backward if built exactly as shown. Some historians think this was an intentional secret safety feature; others consider it a drawing error or an unresolved mechanical problem.

Unlike a modern tank, Leonardo’s vehicle had no engine, tracks, turret, or reliable battlefield record. It is best understood as a remarkable armored war-machine concept rather than the first operational tank.