What oversized artillery weapon did Leonardo da Vinci sketch for the Duke of Milan?

Leonardo da Vinci sketched a giant crossbow as an oversized artillery weapon for the Duke of Milan.

The design appears in Leonardo’s military studies from the late 15th century. It used a very large bow mounted on a wheeled frame, with a winch or mechanical system to draw the string. Leonardo’s drawings also show structural supports intended to keep the weapon stable when it was fired.

The giant crossbow was probably meant to intimidate as much as to cause damage. Its large projectile could have been useful against troops or fortifications, but the scale created serious practical problems involving transport, loading, and the strength of the bow. There is no secure evidence that Leonardo’s specific design entered battlefield service.

This weapon should not be confused with an ordinary medieval crossbow. A crossbow stores energy in a bent bow and releases it through a string; Leonardo’s version enlarged that principle into a siege-scale machine. The concept illustrates how Renaissance engineers adapted familiar weapons for spectacular military proposals.