The most successful minelaying submarine of the war, Rubis was responsible in her 22 minelaying patrols for the sinking of at least 15 vessels. These included five warships as well as vessels running iron ore in coastal convoys to Germany.

France constructed three series of submarines in the period between 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 first postwar French submarines were of the 1922 and 1923 programs and were based on the study of German U-boats taken as reparations. These 9 submarines of the Requin-class had a standard surface displacement of 947 tons and were armed with 10 21.7-inch torpedo tubes, 1 3.9-inch deck gun, and 2 25.2 mm machine guns. The 31 large submarines of the Redoutable class (launched between 1928 and 1937) generally were regarded as very effective boats. They displaced 1,384 tons standard on the surface; their maximum range was 10,000 miles at 10 knots on the surface, and their submerged endurance was 60 hours at 2 knots. They had a battery of 11 torpedo tubes (7 of them in 2 remotely controlled trainable external mounts) with a total of 13 torpedoes and a single 3.9- inch deck gun.

The French also constructed several smaller seagoing patrol-type submarines. A 1922 building program called for 4 600-ton boats. These were the Sirène-class, 9 of which were eventually built. Several other patrol-type submarine classes were authorized in the years before the war, but not all were complete when France fell in June 1940. These submarines displaced between 600 and 900 tons. The Aurore class, the last series of French submarines being constructed when World War II began, displaced 893 tons and were armed with 9 21.7-inch torpedo tubes (3 in an external remotely controlled trainable mount) plus a single 3.9-inch deck gun and 2 13 mm machine guns.

The French minelaying submarines of the Saphir-class displaced 761 tons on the surface and could cruise for 7,000 miles at 10 knots on the surface. They 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 (3 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 at the outbreak of the war. The Surcouf, designed for long-range commerce warfare, displaced 2,880 tons standard on the surface and had a range of 10,000 miles at 10 knots on the surface. It had a range of 60 hours at 2 knots submerged and could operate safely at a depth of 250 feet. The Surcouf ’s battery included no fewer than 12 tubes (8 in external mounts) with 22 torpedoes, 2 8-inch guns in a special turret mounting, and a seaplane stowed in a hangar and launched with a catapult. The Surcouf also was 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 it never operated as designed during combat because of the fall of France and the boat’s subsequent loss in a collision.