French destroyer Le Triomphant

In April 1939, the bridge wings were enlarged to accommodate the Hotchkiss machine guns on Le Triomphant, L'Indomptable and Le Malin. After the war began, 200 kg depth-charge stowage increased to 48 and a pair of rails were installed on the stern for 35-kilogram (77 lb) depth charges. Each rail could accommodate 3 depth charges and 15 more were stored in the magazine. In early 1940 twin-gun 37 mm mounts replaced the single-gun mounts. Under Free French control as of 3 July, Le Triomphant was refitted in late 1940 during which she had her aft superfiring 138.6 mm gun replaced by a British 4-inch (102 mm) Mk V AA gun and a Type 128 ASDIC system that had been taken from a seized French destroyer was installed. The 35 kg depth charges and their rails were removed and the ship was fitted with four Modèle 1918 depth-charge throwers abreast the aft superstructure for 100-kilogram (220 lb) depth charges. Two of these were stowed next to each mount and eighteen more were stowed in the magazine.[5]

During a subsequent refit in mid-1941, the Hotchkiss machine guns were relocated to positions on the forecastle deck and their former positions were occupied by single mounts for 2-pounder (40 mm (1.6 in)) Mk II AA guns. A quadruple mount for Hotchkiss machine guns taken from the battleship Paris was installed atop the aft superstructure and rails for 18 British Mk VIIH depth charges were installed on the stern. A fixed antenna for a Type 286M search radar was also installed. A late 1942 refit in Australia exchanged the 13.2 mm machine guns for six 20-millimeter (0.8 in) Oerlikon light AA guns and the Type 286M radar was replaced by a Type 290 system with a rotating antenna.[6]

En route to the Boston Navy Yard in 1944 for a comprehensive refit, Le Triomphant stopped in Bizerte, French Tunisia, where the British Mk V AA gun was replaced by a 138.6 mm gun from L'Audacieux. The Americans installed SA early-warning, SF surface-search and a British Type 285 fire-control radar, removed her aft torpedo tubes to save weight and converted some boiler feedwater tanks to fuel oil to improve her range. Her AA armament had been removed earlier and now consisted of six 40-millimeter (1.6 in) Bofors guns in a twin-gun mount superfiring over the aft 138.6 mm guns, and two other twin mounts forward of the aft funnel; she now carried eleven Oerlikon guns in single mounts, four on the sides of the bridge and the remaining guns on platforms on the aft superstructure, on the quarterdeck, and where the aft torpedo mount had been.[7]

Both the 8th and 10th Scout Divisions were assigned to the Force de Raid at Brest when war was declared in September 1939; it made only a single sortie as a complete unit on 2–6 September when it responded to an erroneous report that German ships had left port. Afterwards it was dispersed into smaller groups to search for German commerce raiders and blockade runners.[9] During 21–30 October, the Force de Raid, including all of the Le Fantasques, screened Convoy KJ 4 against a possible attack by the heavy cruiser Admiral Graf Spee. On 25 November the 8th Scout Division, consisting of Le Triomphant, L'Indomptable, and Le Malin, rendezvoused with the battleship Strasbourg and escorted her to Brest.[10] Her sister, Dunkerque, sailed for Canada on 11 December with a cargo of gold and she was escorted for the next two days by Le Triomphant, Le Terrible, Valmy, Mogador and Volta.[11]

In anticipation of an Italian declaration of war, the Force de Raid, including the 8th Scout Division, assembled in Mers-el-Kébir, French Algeria, on 5–9 April 1940, only to return to Brest when the Germans invaded Norway on the 10th. On the night of 23/24 April 1940, the 8th Scout Division made a high-speed patrol of the Skaggerak, hoping to attack German merchantmen headed for Norway. They encountered two patrol boats and damaged one of them while also engaging a pair of S-boats to little effect and narrowly missed spotting a convoy of minelayers. Le Malin then began experiencing engine problems and the ships were forced to reduce speed. Near-misses by German bombers damaged one of Le Triomphant's propeller shafts as they withdrew and she returned to Lorient on 30 April for repairs.[12] As the Germans advanced in France and threatened the harbors in Brittany, the ship departed for Plymouth on 21 June.[13]

Le Triomphant having her bow painted by her crew in late 1940

On 3 July she was seized by the British at Plymouth as part of Operation Catapult, but the ship was turned over to the FNFL on 28 August and Commander (Capitaine de frégate) Philippe Auboyneau assumed command of the ship. She was partially refitted with British equipment in September–October and recommissioned on 23 October, although the ship was not ready to go back to sea until November when she was assigned to the 11th Escort Group, based on the Firth of Clyde in western Scotland. Le Triomphant had constant problems with her propulsion machinery and propeller shafts during this time, which were aggravated when she broke loose from her mooring in Greenock during a gale in February 1941 and collided with a cargo ship. The ship received a major refit at HM Dockyard, Devonport in May–July to prepare her for service in the Pacific Ocean for which she departed on 31 July via the Panama Canal.[14] As Le Triomphant passed through the canal on 16 August, she was recognised and reported by a Japanese observer, whose transmission was intercepted by Magic.[15] The ship reached San Diego on 25 August and received some minor repairs before she sailed for Tahiti on 5 September. Le Triomphant transported Georges Thierry d'Argenlieu, the Free French High Commissioner for the Pacific during this voyage and reached Papeete harbor on 23 September. The ship spent the next month visiting many of the islands of French Polynesia and British Fiji before arriving back in Papeete on 22 October.[14]

Starboard aft quarter view of Le Triomphant

At that time, she received orders from the Admiralty to return to the Mediterranean and to be at Suez, Egypt, no later than 13 December. While leaving Wellington, New Zealand, Le Triomphant was damaged by a violent and sudden gust of wind and was under repair in Sydney, Australia, on 8 December when the Japanese attacked Pearl Harbor.[16] In mid-December, she escorted the troopship SS Ormiston from Sydney to Nouméa, New Caledonia,[17] and conducted other escort missions during this time. In late February 1942, as a Japanese invasion of Nauru and Ocean Island was feared, Le Triomphant helped to evacuate the small military contingent and the European and Chinese workers from both islands. The ship resumed her earlier duties before she began a refit at the Garden Island Dockyard in Sydney on 19 March. Completion of the refit was delayed by the heavy workload there and it was not finished until 20 January 1943. Le Triomphant was reassigned to escort duties, mostly between Sydney and Melbourne and she rescued survivors of the torpedoed BHP Shipping iron ore carrier SS Iron Knight off Cape Howe on 8 February. Between 10 February and 23 May, the ship conducted 19 escort missions before entering Williamstown Dockyard in Melbourne for the installation of her port propeller chase on 26 May. Le Triomphant resumed escort missions after the installation was completed on 17 June and Captain (Capitaine de vaisseau) Paul Ortoli relieved Auboyneau in July. The ship was overhauled again in Sydney from 8 September to 7 November. She was reclassified as a light cruiser on 28 September.[18]

On 24 November, a five-man liaison team from the Royal Australian Navy boarded the ship in Melbourne.[19] Le Triomphant departed Fremantle the following day to return to the Mediterranean, accompanied by the American oil tanker SS Cedar Mills. A few days later, an accident while starting to refuel damaged the oil transfer gear, which meant that the cruiser only had 170 metric tons (170 t) of fuel in her tanks; to conserve fuel, Cedar Mills started towing Le Triomphant. The transfer gear was finally repaired on 1 December and she was able to top off her oil tanks. During the night of 2/3 December, the ships were struck by a typhoon and Le Triomphant was badly damaged. She took on a 15 degree list and her forward boiler and engine rooms were flooded. After taking off some of the crew, Cedar Mills was able to re-establish the tow on 5 December. The heavy cruiser HMS Frobisher took over the task and towed the large destroyer to Diego Suarez, French Madagascar, on 19 December. Temporary repairs there took until 21 February 1944 when she sailed for Boston, Massachusetts, for permanent repairs that lasted for a year after her arrival there on 12 April.[20] En route, Le Triomphant stopped at Algiers where she was inspected by General Charles de Gaulle, leader of the Free French, and the High Commissioner for the Navy, Louis Jacquinot.[19] Ordered to the Indian Ocean in 1945, she served with the Eastern Fleet after her arrival in Colombo, Ceylon, on 27 May. After a brief refit in Diego Suarez in July, she covered the British occupation of Singapore in early September together with the French battleship Richelieu.[21]

Le Triomphant was the first French warship to deploy to French Indochina after the war, arriving in Saigon on 3 October 1945 and alternated with Le Fantasque in providing gunfire support to the French garrison at Nha Trang and then supporting French forces on the coast of the Gulf of Tonkin until February 1946. On 6 March she led a convoy to Haiphong which the French were to take over from the Chinese, but they engaged the convoy for 20 minutes before a cease-fire could be negotiated. Le Triomphant was lightly damaged, but 8 of her crew had been killed and 39 wounded. The sisters participated in a naval review in Ha Long Bay on 24 March before Le Triomphant departed for France on 9 April where she arrived at Toulon on 16 May.[22]

The ship was reduced to reserve upon her return and was refitted at Bizerte from February to November 1947. During this time, only two of the four surviving ships of the class were active at any one time because of a shortage of trained personnel. When Le Triomphant arrived at Toulon on 7 February, she relieved Le Malin in the 10th Light Cruiser Division (10^e Division de croiseurs légers). The ship remained on active duty until she was placed in reserve at Bizerte on 1 November 1949. Le Triomphant was sold for scrap in December 1957 and was subsequently broken up.[23]