It was the best French fighter of the war. The first prototype D520 flew in October 1938. After seizing the non-occupied part of France in November 1942, the Germans captured 246 D520C1 fighters, but only 182 of them were airworthy. Repainted and re-equipped they served the Luftwaffe as operational training aircraft. Some of these captured planes were sold to German Allies, some destroyed during the French Campaign in 1944 or recaptured by Free French pilots and the French Resistance.