HMS Fortune was one of nine F-class destroyers built for the Royal Navy in the mid-1930s. Although she was assigned to the Home Fleet upon completion, the ship was detached to the Mediterranean Fleet to enforce the arms blockade imposed by Britain and France on both sides during the Spanish Civil War of 1936–39. Several weeks after the start of the Second World War in September 1939, Fortune helped to sink a German submarine. The ship escorted the larger ships of the fleet during the early stages of World War II and played a minor role in the Norwegian Campaign of 1940. Fortune was sent to Gibraltar in mid-1940 and formed part of Force H where she participated in the Battle of Dakar against the Vichy French. The ship escorted numerous convoys to Malta in 1940–41 until she was badly damaged by Italian bombers in mid-1941.

After repairs were completed, Fortune was briefly assigned to the Mediterranean Fleet before she was transferred to the Eastern Fleet in the Indian Ocean in early 1942. The ship screened an aircraft carrier during the Battle of Madagascar later that year and was assigned to convoy escort duties for the rest of 1942 and early 1943. She returned home in February to begin conversion into an escort destroyer. The ship was transferred to the Royal Canadian Navy (RCN) when it was completed in mid-1943 and renamed HMCS Saskatchewan. The ship spent the next year escorting convoys in the North Atlantic before she was transferred to the English Channel to defend convoys during the Normandy landings in June 1944. Saskatchewan engaged some German patrol boats the following month and was lightly damaged. She was sent to Canada for repairs and a general refit and did not return to the UK until January 1945. The ship resumed her former duties until the end of the war in May and then ferried troops back to Canada for several months. Saskatchewan was judged surplus later that year and was sold for scrap, in early 1946.

The F-class ships were repeats of the preceding E class. They displaced 1,405 long tons (1,428 t) at standard load and 1,940 long tons (1,970 t) at deep load. The ships had an overall length of 329 feet (100.3 m), a beam of 33 feet 3 inches (10.1 m) and a draught of 12 feet 6 inches (3.8 m). They were powered by two Brown-Curtis geared steam turbines, each driving one propeller shaft, using steam provided by three Admiralty three-drum boilers. The turbines developed a total of 36,000 shaft horsepower (27,000 kW) and gave a maximum speed of 35.5 knots (65.7 km/h; 40.9 mph). Fortune barely exceeded her designed speed during her sea trials. She carried a maximum of 470 long tons (480 t) of fuel oil that gave her a range of 6,350 nautical miles (11,760 km; 7,310 mi) at 15 knots (28 km/h; 17 mph). The ships' complement was 145 officers and ratings.

The ships mounted four 4.7-inch (120 mm) Mark IX guns in single mounts, designated 'A', 'B', 'X', and 'Y' in sequence from front to rear. For anti-aircraft (AA) defence, they had two quadruple Mark I mounts for the 0.5 inch Vickers Mark III machine gun. The F class was fitted with two above-water quadruple torpedo tube mounts for 21-inch (533 mm) torpedoes. One depth charge rack and two throwers were fitted; 20 depth charges were originally carried, but this increased to 35 shortly after the war began.

Fortune had her rear torpedo tubes replaced by a 12-pounder (76 mm) AA gun by April 1941. In February–May 1943, she was converted into an escort destroyer. A Type 286 short-range surface search radar was fitted and a Type 271 target indication radar was installed above the bridge, replacing the director-control tower and rangefinder. The ship also received a HF/DF radio direction finder mounted on a pole mainmast. Her short-range AA armament was augmented by four 20 mm (0.8 in) Oerlikon guns and the .50-calibre machine guns were replaced by a pair of Oerlikons. A split Hedgehog anti-submarine spigot mortar was installed abreast 'A' gun and stowage for a total of 70 depth charges meant that 'Y' gun, the 12-pounder and her Two-Speed Destroyer Sweep (TSDS) minesweeping gear had to be removed to compensate for their weight.

Fortune, the 23rd ship of that name in the Royal Navy, was laid down by John Brown & Company at their Clydebank shipyard on 27 July 1933. She was launched on 29 August 1934 and completed on 27 April 1935. The ship cost 247,564 pounds, excluding government-furnished equipment like the armament. Fortune was initially assigned to the 6th Destroyer Flotilla (DF) of the Home Fleet, but detached to the Mediterranean Fleet in 1937 to enforce the arms embargo imposed on both sides in the Spanish Civil War by the Non-Intervention Committee. The 6th DF was renumbered the 8th Destroyer Flotilla in April 1939, five months before the start of World War II.

After a pair of fishing trawlers were sunk by a submarine off the Hebrides after the start of World War II in September 1939, the 6th and 8th DFs were ordered to sweep the area on 19 September. The following day, Fortune and three of her sister ships sank the German submarine U-27 and then resumed their normal escort duties. In February 1940, she was one of the escorts for Convoy TC 3 carrying troops from Canada to the UK. In the following month, while escorting units of the Home Fleet north-west of Shetland on 20 March, she was credited with sinking U-44, although later research suggests that the submarine was destroyed in a minefield which had been laid by other British destroyers on 13 March.

During the Norwegian Campaign, Fortune played a minor role escorting the oiler RFA War Pindari to Namsos on 15 April. On 25 April, she ferried part of the 2nd Battalion, the South Wales Borderers to Bogen and Lenvik. A few days later the ship escorted the aircraft carriers Ark Royal and Glorious and the battleship Valiant off the coast of Norway. In early May, she escorted two cruisers ferrying troops to occupy Iceland. In August, Fortune was briefly transferred to the 4th DF and on 10 August, the ship rescued survivors from the torpedoed armed merchant cruiser Transylvania. Later in the month, she escorted a convoy to Gibraltar and was transferred to Force H on the 28th.