The Dewoitine D.520 was a French fighter aircraft that entered service in early 1940, shortly after the opening of WW II. Unlike the Morane saulnier M.S.406, which was at that time the Armeé de l`Air's most numerous fighter, the Dewoitine D.520 came close to being a match for the latest German types, such as the Messerschmitt Bf-109. It was slower than the Bf 109E but superior in manoeuvrability. Because of a delayed production cycle, only a small number were available for combat with the Luftwaffe.
The D.520 was designed in response to a 1936 requirement from the Armée de l'Air for a fast, modern fighter with a good climbing speed and an armament centred around a 20 mm cannon. At the time the most powerful V 12 liquid cooled engine available in France was the Hispano Suiza 12Y, which was less powerful, but lighter, than contemporary engines such as the Rolls-Royce Merlin and Daimler Benz DB 601. Other fighters were designed to meet the specifications but none of them entered service, or entered service in small numbers and too late to play a significant role during the Battle of France.