Performing its first flight on 2 October 1938, the Dewoitine D.520 was an elegant and nimble monoplane with refined aerodynamics and outstanding performances. It was powered by an in line 12 cylinder Hispano Suiza 12Y45 engine yielding 935hp and allowing a top level speed of 534km/h. Its armament comprised one 20mm HS404 gun firing through the propeller hub and two 7.5mm machine guns in each wing. The first production aircraft made its maiden flight on 31 October 1939. Only 200 out of the 437 aircraft produced before the 25 June 1940 armistice were able to participate to the aerial flights of the French Campaign. Their pilots claimed 108 official aerial victories and 39 probables. Had the Armee de l'Air possessed a few more squadrons of this superb fighter, the fate of the Luftwaffe in the skies of France might have been different.
After the fall of France, the D.520 was use extensively by the Vichy Air Force as well as Free French units. Large numbers were used as advanced trainers by the Luftwaffe.