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
Mitrailleuses were used in many of the major engagements of the Franco-Prussian War (1870–71), but their small numbers greatly restricted their effectiveness. Their flawed usage was a serious problem on the battlefield. While the mitrailleuses were inherently accurate, in a ballistic sense, they were often unable to zero in on targets quickly enough at great distances. Individual 25 round salvos were also too tightly grouped and lacked lateral dispersion. To make matters worse, the complex firing mechanism was vulnerable to damage at the hands of inexperienced crews. Fouling of the mechanism by black powder combustion residues and thus difficulties in closing the breech were reported as a problem after prolonged firings.
In a few instances where the Reffye mitrailleuses were put to good use, they showed that they could have a significant impact. Captain Barbe's mitrailleuse battery at the Battle of Gravelotte devastated massed Prussian infantry when they had quickly found the range on their targets, contributing to the exceptionally high Prussian death toll in that battle. Other examples of effective mitrailleuse fire have also been described for the battles of Saint Privat and Mars-la-Tour. For the most part, however, mitrailleuses proved ineffective. It was concluded after the war that Chassepot rifle fire had caused a far greater number of Prussian casualties than the Reffye mitrailleuses. However, about 100,000 Chassepot rifles were engaged in combat in contrast with the less than 200 Reffye mitrailleuses used in battle at any given time.