Propelled on the surface by two diesel engines producing a combined 6,000 horsepower (4,474 kW), they had a maximum speed of 18.6 knots (34.4 km/h; 21.4 mph).

[6] She conducted two patrols, and the only significant incident occurred when the British cargo ship Egba refused to stop for inspection even after Le Glorieux fired warning shots.

On 17 February 1940 (or in March 1940, according to one source[3]) Le Glorieux and Le Tonnant received orders to escort the British cargo ship SS Hartismere, which had suffered machinery damage, to Freetown in Sierra Leone, but the two submarines did not find the ship due to bad information, and they returned to Dakar.

[3] Many members of their crews initially refused to fight the British, but the commanding officer of Le Héros convinced them to participate in the sortie.

[3][11] During training, Le Glorieux collided with the accommodation hulk Condorcet on 10 September 1941, suffering damage to her stern which required ten days of repair work and delayed her departure.

[3] In October 1941, the British boarded and captured a convoy of four Vichy French cargo ships en route to Dakar.

[3] On either 15 or 16 November 1941, according to different sources,[3] one of the submarines attacked the 4,000-gross register ton cargo ship Capo Olmo, some sources claiming that Le Glorieux fired two torpedoes at her south of the Cape of Good Hope off Port Elizabeth, South Africa, at 35°40′S 019°20′E / 35.667°S 19.333°E / -35.667; 19.333 and that both missed,[3][13] others that Le Héros made the attack during a storm on 16 November 1940 and claimed to have sunk Cap Olmo.

[3] At the end of December 1941, Le Glorieux escorted an aviso on a supply mission from Madagascar to Djibouti in French Somaliland, which the Allies were blockading.

[3] Le Glorieux departed Djibouti on 19 February 1942 in company with the auxiliary cruiser Bougainville bound for Diego-Suarez, which they reached without incident.

[3] At 10:00 on 6 May 1942, she closed to within 10,000 to 12,000 metres (10,900 to 13,100 yd) of the British aircraft carrier HMS Indomitable, but was unable to reach an attack position.

[3] On 7 May 1942, with the British having seized Diego-Suarez, Le Glorieux received orders to withdraw and rendezvous with D'Iberville at Androka on the southwestern coast of Madagascar.

[3] Allied forces landed in French North Africa in Operation Torch on 8 November 1942, and on 9 November the Armistice Commission authorized Le Glorieux and several other French submarines – her sister ships Casabianca and Redoutable as well as the submarines Diamant, Iris, Naïade, Thétis, and Vénus and, according to one source, Le Glorieux′s sister ships Henri Poincaré and Pascal as well – to rearm.

Among the Redoutable-class submarines at Toulon, only Le Glorieux and Casabianca had embarked new batteries and provisions and fully refueled when the Germans arrived.

At the sound of the first gunshots, they and Iris, Vénus, and the submarine Marsouin cast off from Le Mourillon between 05:00 and 05:15 and made a run for the open sea under fire by German forces.

[3][19] The submarines spent the rest of the day submerged south of Toulon, then surfaced after dark to decide on their next moves, some opting to head for Algiers in Algeria and others – including Le Glorieux — for Spain.

[3] Meeting a curt reception by Fascist authorities in Spain – who seized Iris after her arrival in Barcelona on 28 November — and having received orders from the High Commissioner of France in Africa, Admiral François Darlan, to proceed to Algiers, Le Glorieux′s commanding officer decided to put back to sea after only a few hours in port.

In September 1943, she was sent to a United States Navy sound school at Bermuda,[21] where she served as a submerged target for ships engaged in antisubmarine warfare training.

A significant effort went into improving her soundproofing,[22] and radars, more efficient listening gear, a sonar, a new pitometer log, a new bathythermograph,[25] air conditioning, and a refrigerator were installed aboard her.

On 27 July 1944, Chairman of the Provisional Government of the French Republic Charles de Gaulle ordered Le Glorieux and her sister ship Archimède to prepare for a transfer to the Pacific Ocean to participate in the war with Japan, with a target date of 15 November 1944 for their departure,[3][26] but Vice admiral André Lemonnier argued successfully that the two submarines were too old for such remote service, and the plan for them to operate in East Asian waters was dropped.

[3] The Allied invasion of Southern France, Operation Dragoon, which began on 15 August 1944,[27] brought the war in the Mediterranean to an end before Le Glorieux could see further combat.

[30] After completing post-refit sea trials at the beginning of 1947, Le Glorieux and Archimède were based at Brest, France, in January 1947.