What Leonardo da Vinci military machine had a conical shell and was designed to move using internal crews?

Leonardo da Vinci’s military machine with a conical shell and internal crews was the armored fighting vehicle.

Leonardo designed this vehicle in the late fifteenth century as a covered, circular platform with sloping armor. The shape was intended to deflect incoming projectiles. A ring of light cannons around the platform would allow the crew to fire in several directions.

The vehicle was meant to be moved by people turning cranks connected to wheels. Modern reconstructions have shown that the surviving drawing contains mechanical problems, including a gear arrangement that would prevent the vehicle from moving as drawn. Some historians have suggested that this may have been deliberate or caused by a copying error.

Calling it a “tank” is understandable but historically imprecise: the modern tank appeared during the First World War. Leonardo’s machine was an early armored-vehicle concept, not a functioning modern tank.