The MP 18, manufactured by Theodor Bergmann Abteilung Waffenbau, was arguably the first 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 Sturmtruppen, assault groups specialized in trench combat. Although MP 18 production ended in the 1920s, its design formed the basis of most submachine guns manufactured between 1920 and 1960.