French destroyer Léopard

By 7 September 1939, Léopard was no longer a part of the 2nd DCT and was assigned to the Western Command (Forces maritimes de l'Ouest) for convoy escort duties from October to May 1940 where she guarded convoys traveling between Gibraltar and Brest as well as Casablanca, French Morocco, and Le Verdon-sur-Mer. In early 1940, the ship had a British Type 123 ASDIC installed; in addition two depth-charge throwers were reinstalled, No. 3 gun removed, and her depth charge stowage reduced to a dozen 200 kg and eight 100 kg depth charges to improve her stability.[7]

By 22 May Léopard was reassigned to the 2nd DCT when the unit was tasked to carry demolition teams to the northernmost French ports; the ship arrived at Boulogne-sur-Mer that evening.[8] Together with Chacal and eight smaller destroyers, Léopard bombarded advancing German troops as they approached the defenses of Boulogne-sur-Mer, firing the last shots of the battle at midday on 24 May. On 28 May, a special flotilla was constituted under the command of Admiral Marcel Landriau, with his flag on the aviso Savorgnan de Brazza, with these ships and a number of smaller units to support the ongoing evacuation of Dunkirk. On 3 June, the contre-torpilleur rescued 19 British soldiers from a boat and delivered them to England.[9]

In mid-June, Léopard defended the approaches to Cherbourg and sailed to Portsmouth on 19 June, after the port surrendered to the Germans. The ship was still there when Operation Catapult, a British operation to capture or disable the ships of the French Navy lest the Germans seize them and use them against the British, began on 3 July.[10] She was handed over to the Free French Naval Forces on 31 August. Command of Léopard was given to Lieutenant (Lieutenant de vaisseau) Jules Évenou, who went by the nom de guerre of "Jacques Richard".[11]

Léopard was commissioned by the Free French on 3 September although she was under repair until November as the British dockyards were very congested. During this time, the British took the opportunity to improve her anti-aircraft suite. A QF 4 in (102 mm) Mk V AA gun replaced the two 13.2 mm machinegun mounts on the platform abaft the rear funnel, the 13.2 mm guns on the forecastle were moved to positions abreast the fore funnel, and a pair of 2-pounder (40 mm) Mk II "pom-pom" light AA guns were added on platforms on the side of the forward superstructure. Upon the completion of this refit, she was assigned to convoy escort duties in the Western Approaches.[12] On 24 February 1941, Léopard rescued 39 survivors of a British cargo ship.[11]

On 8 May 1941, she began a lengthy conversion into an escort destroyer at Kingston upon Hull. Her forward boiler and its funnel were removed and replaced by additional oil storage and additional accommodation for her ratings. They reduced her maximum speed to 31.5 knots (58.3 km/h; 36.2 mph), but increased her fuel storage to 780 metric tons (770 long tons; 860 short tons) which raised her range to 4,200 nmi (7,800 km; 4,800 mi), and her crew to 234 ratings. Her troublesome depth charge chutes were sealed off and their machinery was removed; her stern had to be rebuilt to accommodate two rails at the stern, each with a dozen 251-kilogram (553 lb) Mk VIIH heavy depth charges, plus an additional four stored below decks. Her two existing depth charge throwers were replaced by four improved Thornycroft Mk IV throwers. The ship carried a total of twenty-four 191-kilogram (421 lb) Mk VII light depth charges for the throwers. To compensate for the weight of the additional depth charges, her aft torpedo tubes were removed. The 4-inch gun was replaced by a single 20-millimeter (0.8 in) Oerlikon light AA gun and two others replaced the "pom-pom"s. These were moved to positions on the upper deck that had formerly been occupied by the 75 mm guns and another gun was added on top of the aft superstructure. A pair of quadruple mounts for Vickers 0.5 in (12.7 mm) AA machineguns were added on the forward superstructure. A Type 291 search radar was also added.[13]

General Charles De Gaulle inspecting sailors aboard Léopard, 24 June 1942

While escorting Convoy OS33 on 11 July 1942, the frigate HMS Spey spotted the German submarine U-136 on the surface and made multiple attacks after the U-boat dived. Léopard joined her, as did the sloop HMS Pelican and they sank the submarine at coordinates 33°28′N 23°28′W.[14] The next day Léopard collided with the sloop HMS Lowestoft and had her bow stove in by the British ship. She was repaired in South Africa in September–October.[15]

Commemorative plaque of the liberation of La Réunion

Léopard had been selected to convince the Vichy government of La Réunion to join the Free French in June, but the collision and her consequent repairs delayed her mission. On the night of 27/28 November, she arrived off the island with 80 troops aboard. They were landed successfully and seized control of Saint-Denis, Réunion, the island's capital, although the governor fled into the interior. A coast-defense battery engaged the contre-torpilleur and she fired back, with men killed on both sides. The Vichy hold-outs surrendered on the 30th and Léopard remained in the Indian Ocean escorting convoys until March 1943.[16]

She was briefly refitted at Diégo-Suarez, Madagascar from 13 March to mid-April when she was transferred to the Mediterranean.[16] Léopard arrived in Alexandria, Egypt, on 12 May and screened a convoy to Malta shortly afterwards. She departed on 24 May with a convoy returning to Alexandria and accidentally ran aground near Benghazi three days later after aerial attacks disrupted the convoy. The Allies attempted to refloat her by sealing damaged areas between her bilges with cement and dredging a channel back to the sea.[17] The weather soured and the wreck broke in two in a gale on 19 June and was declared a total loss on 1 July.[15]