In 1921 the Section Technique de l'Artillerie (S.T.A.) - a wing of the French Army's Technical Commission - was asked to develop the country's first submachine gun. The French Army had a cautious interest in weapons of this type after encountering the Bergmann M.P.18,I, as fielded by the Germans in the late stages of World War I and was now taking steps to evaluate the SMG concept. The S.T.A. promptly drew up plans for a new prototype and the first model was made at the end of 1921, followed by three further prototypes in 1922. Incremental improvements to the design were made until in 1924 the evaluating officers were satisfied with the finalized design and forwarded it to troop trials, with an order of some 100 samples to be produced by the arsenal at St. Étienne. At the same time, St. Étienne were independently developing their own submachine gun prototype - the MAS-24.
Although it is often said that the S.T.A. submachine gun was a copy of the M.P.18,I, it seems likely that the gun was also derived from a French wartime prototype, the Ribeyrolles automatic carbine of 1918, which was a blowback-operated weapon chambered in an experimental 8x35mm cartridge. There may also have been some influence from the Italian Revelli-Beretta carbine. In any case, the basic design of the S.T.A. was not complex. It operated on a straight blowback principle through a tubular receiver mounted to a wooden stock. The magazine feed was vertical, rather than horizontal like the M.P.18,I, and took curved magazines that were similar to the type used by the Villar Perosa. The barrel of the gun was unjacketed, and fitted with a simple bipod, implying intention for a support-fire role. The S.T.A., unusually, did not chamber a French pistol cartridge but instead used 9x19mm Parabellum.
Surprisingly, after brief troop trials in 1924, there was little hesitation in accepting the S.T.A. into service and it was officially adopted on the 11th of August 1925 as the Pistolet Mitrailleur Modèle 1924. The Army purchasing commission placed an order of 8,250 of these guns to be produced by MAS, but problems arose almost instantly. For a start, there was very little idea among the French officer corps as to how the weapon should actually be fielded. The role of a light support weapon was already filled by various machine guns, such as the Chauchat, and with the end of World War I, there was no immediate requirement for a Bergmann-type assault weapon either. The only use the Army could ultimately find for the S.T.A. was to arm "non-tooth" personnel whose job did not require issue of a rifle.
In addition, logistical problems became apparent. As the S.T.A. was not chambered in an existing French cartridge, but rather in 9mm, the Army were also having to purchase new batches of ammunition specifically for this gun, that would be incompatible with any other weapons in service. This proved to be an inefficient investment and it would ultimately prove pointless if the Army could not find a use for the gun.
Although apparently the S.T.A. did see limited use in the Moroccan Rif War of the 1920s, all the issues associated with this gun led to the Army getting cold feet and cancelling the 8,000-gun order in 1928 after only 1,000 had been delivered. The ammunition debacle in particular spurred on the Army's decision to standardize a pistol cartridge, and in the end 7.65mm Longue - derived from the American 7.65mm Pedersen cartridge - was chosen in place of 9mm Parabellum. Purchases of 9mm ammunition ceased and the S.T.A. was thus retracted from service by the early 1930s. The French Army's search for an SMG recommenced a few years later, and development of the MAS-24 - which had been passed over in favour of the S.T.A. - resumed, eventually evolving into the 7.65mm MAS-38 submachine gun. It has been said that some examples of the S.T.A. submachine gun were taken out of storage to be fielded in small numbers during the defence of France in 1940, but if that is true, it must have been in very insignificant numbers.