What Leonardo da Vinci invention was an armored military vehicle moved by eight men turning internal cranks?

Leonardo da Vinci’s invention was an armored fighting vehicle moved by men turning internal cranks.

Leonardo designed the vehicle in the late 15th century as a covered military machine. Its conical, turtle-like shell was intended to deflect projectiles, while a set of wheels beneath the armor would provide movement. The design included a ring of light cannons arranged around the vehicle so they could fire in different directions.

The surviving drawing appears in the Codex Atlanticus. It is commonly described as an early tank concept, although it was never built or used in a historical battle. The design’s proposed crew would turn cranks connected to the wheels, making it a human-powered machine rather than an engine-driven vehicle.

A famous drawing error appears to reverse the gearing in the surviving plan, meaning the vehicle would not move as intended unless the mechanism were corrected. Some historians regard that error as deliberate, while others see it as a drafting mistake. This machine is distinct from Leonardo’s other military designs, including a giant crossbow and a revolving bridge.