"In technological terms Mogador and Volta were ships with the armament of a light cruiser in the hull of destroyer; the contre-torpilleur as a type had been pushed past the limits of its capabilities.

The Rateau-Bretagne geared steam turbines were designed to produce 92,000 shaft horsepower (69,000 kW), which would propel the ship at 39 knots (72 km/h; 45 mph).

During sea trials in March 1938, Mogador's turbines provided 118,320 shp (88,230 kW) and she reached 43.45 knots (80.47 km/h; 50.00 mph) for one hour.

From 21–30 October 1939 the Force de Raid escorted the KJ.4 convoy to protect it against the Deutschland which had sortied into the North Atlantic before the war began.

A sortie by Gneisenau and Scharnhorst into the North Atlantic on 21 November prompted 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.

The necessary improvements identified for the main armament during her sea trials a year prior 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.

4 position, its magazine converted for extra fuel storage, and a new twin 37 mm Mle 1933 mount would replace it on top of the rear deck house.

This plan was later amended to add a degaussing cable, replacement of the SS-6 sonar by a French copy of the British ASDIC and six of the new mitrailleuse de 25 mm contre-aéroplanes Modèle 1940 anti-aircraft guns, plus two more 13.2 mm Brownings mounted on the forward corners of the center deck house.