Mitrailleuse
The first "mitrailleuse" was a manually fired 50-barrel volley gun originally developed in Belgium in 1851 by the Belgian Army Captain Fafschamps, who made a rough prototype and drawings of his invention. The system was improved during the 1850s by Louis Christophe and the Belgian engineer Joseph Montigny, with the completion of the 37-barrel Montigny mitrailleuse in 1863. From 1859, Joseph Montigny proposed his design to Napoleon III, which led to the development of the French Reffye mitrailleuse, designed by Jean-Baptiste Verchère de Reffye with the collaboration of Montigny, and which was adopted by the French Army in 1865. Initially kept under wraps as a secret weapon, it was widely used in battle by French artillery during the Franco-Prussian War (1870–71). Smaller numbers of other designs, including the Gatling gun, were also purchased by the French government during the latter part of that conflict. The Reffye model had initially been built in small numbers and in secrecy: only about 200 were available at the beginning of the conflict. This also kept regular French field artillery in a neglected position in the eyes of French emperor Napoleon III, with dire consequences during the Franco-Prussian War of 1870–71.
Mitrailleuse
In summary, the Reffye mitrailleuse was rarely used to deliver sweeping fire at close range like modern machine guns. The mitrailleuse six-gun batteries had been designed to deliver fire on targets too distant to be reached with Chassepot infantry rifles or artillery grapeshot. To fulfill this role, at least during the early weeks of the campaign, the mitrailleuses were deployed together with the older "Napoleon" muzzle loaded field guns ("canon obusier de 12") used by the French Army during the Franco-Prussian War. The mitrailleuse crews are on record of having generally objected to being placed in proximity to regular artillery batteries .