The MP18 was a German submachine gun designed by Hugo Schmeisser and produced by Theodor Bergmann. Originally conceived as a portable machine gun for trench raids during World War I, the MP18 influenced countless subsequent designs and is now widely considered to be one of the first practical submachine guns in history.
Hugo Schmeisser, then an employee of Theodor Bergmann's factory in Suhl, began working on the MP18 in 1916. The project was initiated in response to a commission from the German Army, who requested a light, automatic, pistol-calibre weapon for trench combat. Bergmann's design was tested but no action was taken until early 1918, when it was finally accepted into service. Production at the Bergmann factory began immediately and the weapon was designated the MP18.I.
Issue of the MP18 was reserved for Sturmtruppen; shock troopers who participated in assaults on enemy trenches. The first MP18s reached the German lines by the Summer of 1918 and only six were issued per company, despite initial plans to issue it to all COs and NCOs. It first saw action during the latter stages of the so-called "Kaiserschlacht" offensive of 1918, and saw little combat usage afterward. Despite this, it still managed to build up a positive reputation with German troops.
Contrary to popular belief, the contemporary reaction to the weapon from the Allied forces was largely apathetic. The British tested captured examples in September 1918 and found little to recommend in the weapon, believing the 9×19mm cartridge to be underpowered and that the weapon could be effectively countered by the use of body armor. An inquiry into whether British troops should be issued with a similar weapon was met with a negative response.
By the end of the war, about 35,000 MP18s had been produced in total. Restrictions imposed by the Treaty of Versailles led to the German Army drastically downsizing its arsenal of machine guns, and consequently most MP18s were taken out of service and issued to German police forces and Freikorps militias. The police issued one MP18 per twenty officers. During the turbulent internal conflicts in post-war Germany, the MP18 saw further combat use by the aforementioned factions.
The MP18 was succeeded by an improved model, the Bergmann MP28, in 1928.