The M.S.406 holds the unfortunate distinction of being the least effective French fighter in service during the Battle of France, which Botquin suggests was due to its relatively low firepower. On 24 June 1940, a M.S.406 flown by Sous Lieutenant Marchelidon of G.C.1/2 scored the French Air Force's last kill in the conflict. Botquin stated of the aircraft: "it would be pointless to pretend, as was often done during the war for propaganda purposes, that the M.S.406 was the finest fighter in the world...but it was certainly a pleasant machine to fly with no vices and great maneuverability".