While the aircraft was very manoeuvrable and could withstand high amounts of battle damage, potentially giving possible advantages during combat against Luftwaffe fighters, the M.S.406 was overall outclassed by the Bf 109. Efforts to replace the M.S.406, such as efforts to convert existing aircraft to the improved M.S.410 standard, with a more capable fighter failed to occur prior to the end of the Phoney War on 10 May 1940, the month in which a massive full-scale invasion by German forces of mainland France commenced, resulting in the Battle of France. On the eve of the invasion, a total of 10 Groupes de Chasse were equipped with M.S.406 fighters, along with a number of defensive units which were almost exclusively equipped with either the M.S.406 or Bloch MB.152 aircraft.