I haven't found any mention of the Gatling gun being used by either side during the Franco-Prussian War. Is there any reason for this? They were being sold abroad by as early as 1867, so there doesn't appear to have been an effort to limit their sales. The French at least were interested in mass-firing weapons, given their poor attempts at fielding the mitralleuse. Thanks
It appears that there were a few Gatlings used by the French during the Franco-Prussian War. Some Gatlings were imported from the US in time for Chanzy's 2nd Army of the Loire to use them in one of the last battles of the War, at Le Mans in January 1871. Reference: The Gatling Gun by Wahl and Toppel (1971).
Thanks for the source, I'll check that out!