Leonardo da Vinci’s famous armoured vehicle resembled a turtle in its overall shape.
The design showed a low, conical, armoured shell covering a wheeled vehicle. Cannons projected around the perimeter, allowing the crew to fire in several directions. The sloping covering was intended to deflect incoming projectiles and protect the people inside.
Leonardo prepared the concept in the late 15th century while working on military engineering. It is often described as an early tank, although that term belongs to modern armoured vehicles and was not used by Leonardo. The proposed machine was to be moved by people turning cranks connected to the wheels.
A famous drawing contains a gearing problem that would prevent the wheels from turning correctly if built exactly as shown. Some historians think the error may have been deliberate, while others regard it as a design mistake. Either way, the turtle-like silhouette is a central feature of the surviving concept.