The MP40 was a submachine gun in service with the German Wehrmacht from 1938 to 1945 during World War II. The gun was nicknamed the "Schmeisser" after its designer, who had patented the magazine for the gun; however, the gun itself was not invented by Schmeisser. 1,100,000 MP40s were produced during the war, rivaling the Karabiner 98k as the main weapon of the Heer. However, the StG 44 was later designed to replace the MP40.