Форум Breguet's Aircraft Challenge

This small fighter was designed and built in France, where a few were used as trainers.
  Belgium ordered 30 for frontline use, but its extremely poor control caused the order to be cut to 10, or perhaps as many as 18, and it is not thought that any were actually used operationally.
  Apparently the prototype was flight-tested by a number of pilots, including Charles Nungesser, who flew the M.1 on 29 January 1916. During that flight the aircraft crashed and Nungesser broke both legs and his jaw. From what I read the Po.M.1 was not put into production for the French military, yet some M.1s were sent to the training schools. None however equipped operational units.
  Thirty were ordered by Belgium because of their inability to recieve enough Nieuports. Discovering what the French already knew, these aircraft were modified by having the cone de penetration deleted, the tailplane and elevators enlarged, and a fixed fin fitted. Willy Coppens noted that the M.1 remained unstable even after these alterations and consequently the initial order of 30 was reduced to (approx.) 10, which I believe, were never used operationally.