Mogador and Volta comprised the 6th Large Destroyer Division (6e Division de contre-torpilleurs) and were assigned to the Force de Raid based at Brest when the war began. This group's purpose was to hunt German blockade runners and raiders and to escort convoys that might be in danger from the same. From 21 to 30 October 1939 the Force de Raid escorted the KJ.4 convoy to protect it against the German cruiser Deutschland which had sortied into the North Atlantic before the war began. A sortie by the German battleships Gneisenau and Scharnhorst into the North Atlantic on 21 November prompted the Force de Raid to sail from Brest to rendezvous with the British battlecruiser HMS Hood and patrol the area south of Iceland, but the German ships were able to return safely under the cover of heavy weather without being engaged.

Both ships were refitted in early 1940 and a number of minor changes were made. The necessary improvements identified for the main armament during their sea trials a year earlier were finally implemented, the canvas cover for the back of the turrets was replaced by a rolling door, new radios were installed, and shields were fitted to the anti-aircraft machine guns and the searchlights. A SS-6 sonar was fitted in June 1940, but proved to be ineffectual.

During the British attack on Mers-el-Kébir on 3 July 1940, Mogador was severely damaged by a hit from a 15-inch (38 cm) shell in the rear hull that detonated her ready depth charges. Volta was also present, but managed to escape in company with the battleship Strasbourg and other ships. Mogador was repaired enough to reach Toulon several months later, but was still undergoing repairs and modifications in Toulon in November 1942. Both Mogador and Volta were scuttled in Toulon Harbour on 27 November 1942 to prevent their capture by Germany. Both were refloated in 1943 by the Italians, but neither was repaired and both were eventually broken up.