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. Although MP18 production ended in the 1920s, its design formed the basis of most submachine guns manufactured between 1920 and 1960.
The MP18 primarily served in final stages of World War I in 1918, especially in the so-called Kaiserschlacht offensive. At least 5,000 MP18.1 were built and used during World War I.
It saw action in South America during the Chaco War, in the Spanish Civil War, and in China during the Japanese invasion where its use by Chinese troops. The MP18 continued in use with German police forces after the end of the war. It was widely used in combat by the Freikorps.
It was later replaced by the MP-28.
A soundly engineered piece of equipment with near commercial grade fittings and finish, the MP18 was a heavy weapon, weighing over 5 kg (11.0 lb) when fully loaded.
MP18 be adapted to use the 32 round TM 08 Luger "snail" drum magazine that was widely used with the long barreled version of the P 08 pistol known as the Artillery model.