The Mogador class was authorized in the 1932 Estimates as an improved version of the Le Fantasque class with three new twin mounts carrying the same Canon de 138 mm Modèle 1929 gun as the earlier ships, but construction was suspended for a period while France and Italy negotiated some limits on their fleets and because the shipyards were already at full capacity.

During this pause time was taken to modify the design to deal with the severe weather and conditions of the North Atlantic and to incorporate developments in propulsion technology that indicated that a larger hull could be used without any requiring any increase in weight.

After a proposal for a catapult was abandoned because of insufficient reserve stability, an extra twin turret was decided upon to boost the ship's firepower.

[1] Their construction was strengthened to handle the severe weather conditions of the North Atlantic as one of the requirements for their intended role as scouts and escorts for the Dunkerque-class battleships of the Force de Raid.

The lack of room in the hull forced a number of workshops and offices into the superstructure which added more weight high in the ship.

There were three deckhouses abaft the break in the forecastle with intervals between them to permit the beam torpedo tubes to rotate, but these were no larger than in earlier ships which meant that space was at a premium.

"They were very steady ships, with a gentle roll period of seven seconds; they heeled only 2-3° with a strong cross-wind, and at only 7-8° at full rudder — a marked improvement over earlier contre-torpilleurs.

This didn't work properly and several ship's captains recommended that the cruise turbines be deleted from future classes entirely.

[5] Arguably the greatest weakness of these ships lay in their inability to generate sufficient electric current to power the multitude of auxiliary motors on which their advanced machinery and complex gun mountings were dependent.

The latter provided only for the ship's minimum lighting and electricity needs, and fires had to be lit in at least one of the boilers in order to train the turrets or elevate the guns for practice or maintenance.

Many of the auxiliary motors themselves were also seriously underpowered, particularly the servomotors for the gun mountings (which were slow to train and elevate) and for the rudder which contributed to the ship's poor maneuverability.

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

The shells and their powder charges were transferred to a tipping drum that was rotated to match the bearing angle of the guns and then loaded.

Some fixes were identified, notably modifications to the breech, installation of split loading trays and reinforcement of the catapult rammers, but they had to wait until the ships' next refit to be implemented.

[8] Five-round ready racks for each gun were added to the sides of the turrets during the refit to compensate for any problems with the loading systems.

It had a conventional sliding breech and used six-round cartridge boxes which gave it a maximum rate of fire of only 30-40 rounds per minute.

This required a loader to move forward 50 metres (55 yd) to pick up each 12.8-kilogram (28 lb) cartridge box and carry it back to the waiting gun crew.

Initially they were mounted on each side of the forward superstructure at deck level and fitted with gun shields to protect them against the spray.

Trials revealed the limitations of these positions with poor arcs of fire and the gun shields obstructed the aimer's view of the target.

However this was not without cost as her torpedo broadside was weaker by one tube than the older class, but the extra launchers positioned close to the ship's side imposed, more importantly, a weight and stability penalty.

[13] Four improved Mogador-class ships were ordered in 1939 to be named Kléber, Desaix, Hoche and Marceau, but their construction was suspended due to the start of World War II.

Their design was continually modified in light of wartime experience, but the original plan for dual-purpose 130 mm (5.1 in) guns had to be shelved when it became apparent that they could not be developed in a timely manner, and they reverted to the main armament of the Mogadors.

From 21 to 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 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.

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.

[16] 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.