Mitrailleuse is a general French term that has been used to identify a specific battlefield weapon relying on multiple barrels. Unlike a traditional "Gatling Gun", in which multiple barrels are aligned with the firing chamber in succession, the Mitrailleuse was categorized as a "volley" gun for all of its barrels fired at once (or nearly all at once). As such their battlefield use was more akin to a set artillery piece (a Line-Of-Sight field gun) than a mobile, offensive gun platform and held little similarity with the machine gun as we know it today.
The earliest Mitrailleuse weapons emerged from Belgium in 1851 and the most notable form was the brainchild of Belgian Army Captain Toussaint-Henry-Joseph Fafschamps. Joseph Montigny of Fontaine-I'Eveque (Brussels) manufactured these first examples and the design was taken on by the Belgian Army in limited numbers to be used to defend Belgian forts. This version carried 50 barrels.
In 1863, the Montigny Mitrailleuse debuted as an improved model with 37 barrels and was also taken on by the Belgians. The newer weapon featured a two-wheeled carriage with tow-arm for transport and a brass cylinder encompassed the barrel assemblies. Loading / reloading was accomplished by way of a pre-loaded ammunition "plate" inserted at the breech-end of the weapon. 11mm Foil cartridges were used to contain the propellant charges and bullets. Overall weight of the complete system was 2,000 lb.
It was not long before the French Army showed interest in the Belgian creation and introduced the weapon into its inventory in 1869. The Montigny was, therefore, a part of French actions in the upcoming Franco-Prussian War (1870-1871). By this time, the French Army could call on about 190 of the guns and six were assigned to a battery as part of an Army division. Their value at short-to-medium ranges was considerable especially in the face of enemy cavalry and infantry charges where scores were slaughtered under the bullets of these guns. However, as with the Gatling Gun of the American Civil War (1861-1865), the Montigny guns were generally operated as set artillery pieces and, in some cases, gunnery crews attempted to volley shots with Prussian artillery elements with little success due to the weapon's range. The tactical value of the Mitrailleuse lay in supporting infantry and defending positions rather than hunting down enemy units at range.
Additional Mitrailleuse guns were manufactured from 1866 onward in France from a local French design as the "Reffye Mitrailleuse" though the concept remained the same.