The M.S.406 was a French Armée de l'Air fighter aircraft built by Morane-Saulnier starting in 1938. Numerically it was France's most important fighter during the opening stages of World War II.
In late 1930s a war with Germany was clearly looming, and the Armée de l'Air placed an order for 1,000 airframes in March 1938. Morane-Saulnier was unable to produce anywhere near this number at their own factory, so a second line was set up at the nationalized factories of SNCAO at St. Nazaire converted to produce the type. Production began in late 1938, and the first production example flew on 29 January 1939. Deliveries were hampered more by the slow deliveries of the engines than by lack of airframes.
Although sturdy and highly manoeuverable, it was under-powered and weakly armed when compared to its contemporaries (such as Hurricane Mk I and Bf 109E) . Most critically, it was out-performed by the Messerschmitt Bf 109E during the Battle of France. The M.S.406 held its own in the early stages of the war (the so-called Phoney War), but when the war restarted in earnest in 1940, losses to all causes amounted to approximately 400 aircraft. Out of this total some 150 were lost to enemy fighters and ground fire, another 100 were destroyed on the ground in enemy air raids and the remainder was deliberately destroyed by French military personnel to prevent the fighters from falling into enemy hands intact. In return M.S.406 squadrons achieved 191 confirmed victories and another 83 probable victories. The type was more successful in the hands of Finnish and Swiss air forces who developed indigenous models. The Finns used the aircraft most successfully, and most surviving MS-406’s were later converted to “Morko-Moranes” by installing captured Russian Klimov M-105P engines rated at 1,100 hp. This greatly improved the performance of the aircraft, and these remained in Finnish service until well after the end of the war.
Late, Germany took possession of a large number of M.S.406s and the later M.S.410s. The Luftwaffe used a number for training, and sold off others. Finland purchased additional M.S.406s (as well as a few 406/410 hybrids) from the Germans, while others were passed off to Italy and Croatia. Those still in French hands saw action in Syria against the RAF, and on Madagascar against the Fleet Air Arm. Both Switzerland and Turkey also operated the type, the Swiss actually managing to down a number of both German and Allied aircraft, 1944-1945.