The French submarine fleet of World War II was one of the largest in the world at that time. It saw action during the World War II, but had a chequered service history due to the complications created by France’s position during the war. During the conflict, 59 submarines, over three-quarters of its total strength, were lost.
While being designed by different bureaux, the French submarines of this period shared a number of features. They were generally double-hulled, with an emphasis on good surface handling, though this led to them being indifferent divers. They also emphasized habitability, needing to be suitable for service in France’s colonial empire, which could mean long voyages and operations in the tropics.
One unique feature was the use of external torpedo mounts. As well as torpedo tubes in the bow and stern, most French submarines carried torpedo tubes externally in trainable mounts, built into the outer casing. These could be trained to fire at various angles beyond fore and aft, but could not be re-loaded at sea. French submarines also mounted torpedoes of different calibres, typically carrying the 400mm (15.75 inch) torpedo, for use against “soft” targets such as merchant ships, as well as the 550mm (21.7 in) torpedo for use against warships.
The role of the French submarine force in 1939 was to act in concert with the French fleet and with France’s allies against the Axis powers, with particular responsibilities in the Mediterranean. It also operated in defence of France’s overseas territories and colonial empire. This changed in 1940 with the fall of France and the signing of the armistice with Germany.
One submarine had been sunk in action, and several others scuttled to prevent their capture; seven others, in British ports at the time of the armistice, became part of the Free French naval force (FNFL). The captured Aurore class boat Favorite was taken into German service as UF-2, a training ship. However the majority remained under the control of the Vichy government.
Over the next two years 16 submarines were lost in Vichy service, mostly in clashes with British and Allied forces.
In November 1942, with the invasion of Vichy territory by the Germans, many of the remaining vessels were scuttled, or captured by the Axis. Those that survived, or managed to escape, joined the FNFL; despite losses, and with replacement from allied navies, France ended the war with 20 submarines in service, having lost 50 boats from a variety of causes.
France constructed three series of submarines in the period be- tween the wars: large, oceangoing, long-range vessels for worldwide service and for operation with the fleet; smaller boats for offensive patrols in European waters; and a successful group of minelayers. The 31 large submarines of the Redoutable class were generally regarded as very effective boats. They displaced 1,384 tons standard on the surface, with a maximum range of 10,000 miles at 10 knots on the surface and a submerged endurance of 60 hours at 2 knots. They had a battery of 11 torpedo tubes (seven of them in two re- mote-controlled, trainable external mounts), with a total of 13 torpedoes and a single 3.9-inch deck gun. The series of smaller patrol submarines began with 12 boats of the “600-tonne” type, followed by 30 of an improved “630-tonne” model, several of which were still incomplete when France fell in June of 1940. They had a range of 4,000 to 5,600 miles at 10 knots on the surface, an underwater endurance of 48 hours at 2 knots, and a safe operating depth of 330 feet. The torpedo battery comprised 9 tubes (three in an external, re- mote-controlled trainable mount) with a total of 9 torpedoes, plus a single 3.9-inch deck gun. The minelayers displaced 761 tons, could cruise for 7,000 miles at 10 knots on the surface, had a submerged endurance of 48 hours at 2 knots, and could safely operate to a depth of 250 feet. They carried 5 torpedo tubes (three in a trainable external mount) with 7 torpedoes, 32 mines, and a single 3-inch deck gun.
The French Navy also operated the largest submarine in the world between the two world wars. The Surcouf was designed for long-range commerce war and displaced 2,880 tons standard on the surface, had a range of 10,000 miles at 10 knots on the surface and 60 hours at 2 knots submerged, and could operate safely at 250 feet. The Surcouf’s battery included no fewer than 12 tubes (eight in external mounts) with 22 torpedoes, two 8-inch guns in a special turret mounting, and a seaplane stowed in a hangar and launched with a catapult. The Surcouf was also equipped with a special compartment to accommodate prisoners taken from intercepted vessels and a small motor launch to transport boarding parties. The submarine proved to be successful in peacetime but never operated as de- signed during combat because of the fall of France and the boat’s subsequent loss in a collision.
Type 1 grand patrol/ocean-going submarine
Requin class: 9 units built 1928–1931
Redoutable class : 31 units built 1928–1937
Redoutable(1st series) : 19 units 1928-31
Espoir (2nd series) : 6 units 1931-34
Agosta (3rd series) : 6 units 1934-37
Type 2 coastal/sea-going submarines
Sirène class : 4 units built 1925–1926
Ariane class : 4 units built 1925–1927
Circé class : 4 units built 1925–1927
Argonaute class : 5 units built 1929–1932
Orion class : 2 units built 1931
Diane class : 9 units built 1930–1932
Minerve class : 6 units built 1934–1938
Aurore class : 8 ordered; 1 completed by 1939
Phénix class : 13 ordered; none completed
Type 3 minelayer submarines
Saphir class : 6 units built 1928–1935
Émeraude class : 4 ordered; none completed
Surcouf : 1 unit built 1929
In addition, Free French forces operated Curie, a British built U-class submarine.