Operational service
Battle of France
The Groupe de Chasse I/3 was the first unit to get the D.520, receiving its first planes in January of 1940. These were unarmed and used for training. In April and May they received 34 production machines, which proved to be very popular with the pilots. In tests against a captured Bf 109E-3 (which didn't develop full power) the D.520 proved to be 20 km/h slower, but had better high speed manoeuvrability. The D.520 matched the turning circle of the Bf 109 but displayed nasty departure characteristics, spinning out of the turn repeatedly during the tests while the Bf 109 owing to its slats could sustain the turn on the edge of the stall easily.
When Germany invaded France and the Low Countries on May 10, 228 D.520s had been manufactured, but the Armée de l'Air had only accepted 75, as most others had been sent back to the factory to be retrofitted to the new standard. As a result, only GC I/3 was fully equipped with the D.520, with 36 planes. They met the Luftwaffe on May 13, shooting down three Henschel Hs 126s and one Heinkel He 111 without loss. GC II/3, GC III/3, GC III/6 and GC II/7 later completed their conversion to the D.520 and all took part in the Battle of France. A naval unit, the 1st Flotille de Chasse, was also equipped with the D.520. GC II/6 and GC III/7 converted to the D.520 but too late to see action.
By the time of the armistice at the end of June, 437 D.520's had been built and 351 of these had been delivered. In that time they had 108 confirmed kills and 39 probables, losing 54 to enemy action. As French resistance collapsed in the middle of June, GC I/3, II/3, III/3, III/6 and II/7 flew their aircraft to Algeria. Three more, from GC III/7, escaped to Britain and 153 machines remained in France.
Under Vichy
In April 1941 production was started again and in June, 550 were ordered to replace all other single-seat fighters. The plan was to have the D.520 eventually equip a total of 17 Groupes with 442 aircraft, three Aéronavale escadrilles with 37 aircraft each plus 3 training units with 13 aircraft. As per terms of the Armistice with Germany, all improvements were prohibited and planes of the new batch were similar with the ones manufactured one year earlier.
D.520s of GC III/6, II/3 and naval escadrille 1AC faced the allies during the Syria-Lebanon campaign in 1941, where they claimed 31 kills over British and Australian planes, while losing 11 of their own in air combat and 24 to AAA, accidents, and attacks on their airfields.
During Operation Torch, GC III/3 (who was really GC I/3 renamed, as the previous unit with this designation had been disbanded) opposed the Allies over Oran, while Flottile 1F saw some action versus the US Navy over Casablanca. Many planes were destroyed on the ground.
Late and postwar service
In December 1942, as French forces formerly under Vichy had sided with the Allies, there were 153 D.520s left in French hands in North Africa. They flew a few patrols during the Battle of Tunisia, but were considered obsolete, and their radio sets were incompatible with Allied equipment. From early 1943 on, they were relegated to training duties at the fighter school in Meknes, and progressively replaced by Spitfires and P-39s in combat units.
During the liberation of France, a few examples abandoned by the Germans were used by ad hoc units in ground attacks against the isolated German pockets of resistance on the Western coast.
Postwar, those that remained in France were used as trainers, serving in this role until 1953.
Foreign users
As the German forces invaded Vichy's so-called "free zone" in November 1942, they captured 246 D.520s; additionally, a new batch of 130 was built under German occupation. Some were used by the Luftwaffe for training purposes. The Germans also transferred 120 D.520s to Bulgaria and 60 to Italy.
