Leonardo da Vinci’s enormous bow for launching heavy projectiles was the giant crossbow.
Leonardo designed the machine in the late fifteenth century, probably as a siege weapon. His drawings show a bow of extraordinary width mounted on a wheeled frame. A mechanical winding system would draw back the bowstring, while a release mechanism would launch a large bolt or possibly a stone.
The weapon was intended to intimidate as well as attack. Leonardo’s notebooks contain many military-engineering designs made during his work for powerful patrons, including Ludovico Sforza in Milan. The giant crossbow reflects Renaissance interest in combining spectacle, mechanical force, and battlefield engineering.
It is not the same weapon as a ballista, which was an ancient torsion-powered missile engine, or a trebuchet, which used a swinging counterweighted arm. Leonardo’s design retained the basic bow-and-string principle of a crossbow, but enlarged it to an impractical scale. No reliable evidence shows that the original machine was completed or used in battle.