The D.500/D.501 saw combat with several operators. During the Spanish Civil War, it was surreptitiously supplied to the Spanish Republican Air Force; it was also flown by the Republic of China Air Force against the invading Japanese during the Second Sino-Japanese War. During the late 1930s, the type was largely superseded by a new generation of French fighter aircraft, these typically featured further innovations such as enclosed cockpits and retractable undercarriages, and included the design's direct successor, the Dewoitine D.520. Despite being largely obsolete, both D.500s and D.510s were operated by the French Air Force during the initial months of the Second World War, the latter remaining in use up to the end of the Battle of France and signing of the Armistice of 22 June 1940 between France and Nazi Germany.