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
The 13 mm centerfire Reffye mitrailleuse cartridges were loaded into interchangeable steel breech blocks, unlike the Montigny mitrailleuse, whose ammunition was held by the cartridge base in plates. When firing the mitrailleuse, three breech blocks were kept in continuous use: one being fired, one being pressed down on the extractor and one being loaded from a single pre-packaged 25-round box. Adjusting the elevation of the mitrailleuse in accordance to the distance to the designated target was performed with an elevating screw identical to that on a regular artillery piece. The mitrailleuse's barrel could also be moved sideways while firing, to the right and left, in order to adjust for range and provide lateral sweeping fire if needed. The lateral sweep was narrow, however, thus most effective at far distances only. The weapon's field of fire was so narrow that Prussian soldiers were often hit by several bullets at once. During an early engagement of the Franco-Prussian War, at Forbach in Alsace on August 6, 1870, a Prussian general officer (General Bruno von François) was brought down by a very closely spaced volley of four bullets. According to the Prussian regimental record, those four mitrailleuse bullets had been fired from 600 meters away. French artillery attempted to rectify this problem by developing special ammunition capable of firing three bullets from the same cartridge for short-range point-defence.