Bolt (breech block) Part of MP-18 I SN 979. IN SMG. Submachine gun, Bergman MP 18 I, 1918, Serial number 979. The World's second SMG, following Italian Villar-Perosa and preceding the Thompson (which was the first to be named as a "Submachine gun"). The MP18.1 manufactured by Theodor Bergmann Abteilung Waffenbau was the first practical submachine gun used in combat. It was introduced into service in 1918 by the German Army during World War I as the primary weapon of the Stosstruppen, assault groups specialized in trench combat.