Submachine Gun - Bergman MP 18 I, 1918, Serial number 979. The attached photo from the website of Colin Stevens shows this body armour, a German WW I MP-18 submachine gun and a German Gewehr KAR 98 rifle. It was displayed in Case 3B of the Old Museum at the Seaforth Armoury. THE 1991 FIREARMS LIST STATES THAT THIS FIREARM IS DEACTIVATED. 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.