Editing Submachine gun (section)

===World War I===
Stocked pistols were common at the beginning of the 20th century, the Germans initially using heavier versions of the [[Luger pistol|P08]] [[pistol]] equipped with a detachable stock, larger-capacity snail-[[drum magazine]] and a longer [[Gun barrel|barrel]]. 

In 1915, the [[Kingdom of Italy]] adopted Revelli's design as the [[Villar-Perosa aircraft machine gun|FIAT Mod. 1915]]. It fired pistol-caliber [[9mm Glisenti]] ammunition, but was not a true submachine gun, as it was originally designed as a mounted weapon.[[File:Brzostrelka Hellriegel - 1.jpg|thumb|A [[Standschütze Hellriegel M1915]], the first submachine gun with a buttstock, seen here with stick and drum magazines]]In late 1915, the first submachine gun with a buttstock was built: the Austro-Hungarian [[Standschütze Hellriegel M1915]] although the weapon was never used in combat.

In February 1916, the Austro-Hungarian first fielded the M.12/P16 machine pistol. This was the first [[machine pistol]] to be adopted by any military, being  issued to Tyrolean units fighting in the Alps<ref>{{Cite web |title=Steyr M.1912/P16 machine-pistol |url=http://firearms.96.lt/pages/Steyr_M.12_P16.html |access-date=2023-06-18 |website=firearms.96.lt}}</ref>

In 1916, Heinrich Senn of Bern designed a modification of the Swiss Luger pistol to fire in single shots or in full-automatic. Around the same time Georg Luger demonstrated a similar Luger machine pistol which inspired the German Army to develop submachine guns.<ref>{{Cite web |title=Maschinenpistole Senn (Luger conversion) |url=http://firearms.96.lt/pages/Senn.html |access-date=2023-06-18 |website=firearms.96.lt}}</ref>

Colonel Bethel-Abiel Revelli had already conceived the principles of the submachine gun in September 1915, when he wrote that his gun could be converted to a single-barreled version that ''"may be mounted in the manner of a rifle so that it may be fired from the shoulder"''. The [[Villar Perosa aircraft submachine gun|FIAT Mod. 1915]] would be later modified into the [[OVP 1918]]  automatic carbine. The OVP 1918 had a traditional wooden [[Stock (firearms)|stock]], a 25-round top-fed [[box magazine]], and had a cyclic [[rate of fire]] of 900 rounds per minute.

By 1918, Bergmann Waffenfabrik had developed the [[9×19mm Parabellum|9x19mm Parabellum]] [[MP 18]], the first practical submachine gun. This weapon used the same 32-round snail-drum magazine as the Luger P-08. The MP 18 was used in significant numbers by German [[Stormtroopers (Imperial Germany)|stormtroopers]] employing [[infiltration tactics]], achieving some notable successes in the final year of the war. However, these were not enough to prevent [[German Revolution of 1918–1919|Germany's collapse]] in November 1918. After World War I, the MP 18 evolved into the MP28/II SMG, which incorporated a simple 32-round [[box magazine]], [[selective fire]], and other minor improvements.<ref>Military Small Arms of the 20th Century. 7th Edition. by Ian V. Hogg & John S. Weeks. Krause Publications. 2000. pages 116</ref> Though the MP18 had a rather short service life, it was influential in the design of later submachine guns, such as the [[Lanchester submachine gun|Lanchester]], [[Sten]] and [[PPD-40]].<ref name=McNab2015>{{Cite book|last=McNab|first=Chris|title=The World's Greatest Small Arms: An Illustrated History|year=2015|pages=61}}</ref>[[File:Bergmann MP18.1.JPG|thumb|A Bergmann MP 18, the first mass-produced submachine gun to see extensive use in an assault role]][[File:Thompson-and-his-gun.jpg|thumb|General [[John T. Thompson]] holding a [[Thompson submachine gun|Thompson Model 1921]]]]
The [[.45 ACP]] [[Thompson submachine gun]] had been in development at approximately the same time as the Bergmann and the Beretta. However, the war ended before prototypes could be shipped to Europe.<ref name="Frank Iannamico 1928">Frank Iannamico, ''American Thunder: The Military Thompson Submachine Gun 1928, 1928A1, M1, M1A1'', Moose Lake Publishing, 2000.</ref> Although it had missed its chance to be the first purpose-designed submachine gun to enter service, it became the basis for later weapons, and was much more successful than the submachine guns produced during World War I.