Which Leonardo da Vinci design is considered an early armored fighting vehicle?

Leonardo da Vinci’s early armored fighting vehicle is commonly called Leonardo’s tank.

Leonardo designed the vehicle in the 1480s, probably while seeking military commissions from Ludovico Sforza, ruler of Milan. His drawing shows a conical, turtle-like armored shell mounted on wheels. The vehicle was intended to carry several men and fire guns through openings in its protective covering.

The design is often called a tank because it resembles a very early armored combat vehicle, although the word “tank” belongs to much later military technology. Leonardo’s machine was never built for Renaissance warfare, and its proposed propulsion system has a famous apparent flaw: the internal cranks seem arranged so that the wheels would turn in opposite directions.

Some historians and engineers suggest that this contradiction may have been deliberate, concealing the design from unauthorized readers or recording an unfinished concept. The vehicle therefore remains an important military-engineering idea rather than a proven operational tank.