What weapon did Leonardo da Vinci design with a giant bow for launching oversized bolts?

Leonardo da Vinci designed a giant crossbow for launching oversized bolts.

Leonardo’s giant crossbow drawing dates to the late fifteenth century and presents an enormous bow mounted on a wheeled frame. The machine was intended to create a powerful psychological and military effect, as much through its impressive size as through its projectile. A winch or mechanical system would help draw the bowstring back against the heavy tension.

The design reflects Leonardo’s habit of combining weapon design with mechanical experimentation. He studied leverage, springs, wheels, and the transmission of force, all of which appear in the proposed crossbow. The weapon was not a normal hand-held crossbow enlarged without modification; its frame and loading mechanism were essential to making the concept workable.

There is no firm evidence that Leonardo’s giant crossbow entered battlefield service. Like many of his military designs, it survives mainly as a detailed proposal intended to demonstrate technical ingenuity to powerful patrons.