At the beginning of the 15. Century the bombard was constructed. It was much more accurate than the traditional siege engines, able to fire balls of stone and crumble even the thickest wall. Thus Constantinople, which had defended itself successfully against the east for a thousand years, was finally captured in 1453 by Sultan Mohammed the Conqueror by the use of bombards. Although the bombard was very powerful, it was almost impossible to move, which severely limited its strategic use.

Large bombard, the Pumhart von Steyr. It fired 32 inches (80 cm), 1500 pounds stone balls.

Between 1465 and 1477 the gun design was improved dramatically. It was discovered, that a small iron cannon ball could do more damage than the large stone balls (which fractured on impact) could. It was thus possible to make new guns which were much smaller (6-8 feet (1,8-2,4 m) long), but more powerful than the old bombards. The small size allowed the guns to be mounted on wheels, and thus be mobile. This meant, that only in areas of very rough terrain, where the new guns could not be used, were the old castle-walls safe. This advantage of the attacker over the defender lasted until the emergence of the Trace Italienne around 1530.