Pmilitary projectile used for cannon shots during siege warfare, the stone cannonball appeared in the late Middle Ages. Very similar to catapult or trebuchet projectiles, it differs from them only by its more regular geometric shape. This one dates from the 15th century and was discovered in the city of Nancy. It testifies to one of the major military techniques of the Middle Ages based on siege warfare and the attack of walls by the use of propulsion weapons. This type of stone ammunition was gradually replaced by cast iron cannonballs from the 16th century onwards, allowing for a reduction in their weight and a gain in performance.