21 cm Mörser 99 mortar

The 21 cm Mörser 99 (Abbr. 21 cm Mrs 99) was a German siege mortar built by Krupp which served during World War I. The mortar utilized a new nickel-steel alloy of greater strength than other cast cannons, though it lacked a recoil mechanism. While the gun was more effective than previous models, it was soon phased out because of improved field artillery and counter-battery fire, though it remained in service in limited numbers throughout the war because of heavy German losses.