HMS Mallow was a Flower-class corvette commissioned into the Royal Navy that served as a convoy escort during World War II; with the Royal Navy in 1940–1944, and with the Royal Yugoslav Navy-in-exile in 1944–1945. In Yugoslav service she was renamed Nada. Her main armament was a single 4-inch (100 mm) Mk IX naval gun, although a significant number of secondary and anti-aircraft guns were added towards the end of the war. During the war she escorted a total of 80 convoys whilst in British service, sinking one German U-boat, and escorted another 18 convoys whilst in Yugoslav service. After the war she served in the fledgling Yugoslav Navy as Nada then Partizanka, before being returned to the Royal Navy in 1949. Later that year she was transferred to the Egyptian Navy in which she served as El Sudan until she was discarded in 1975.
The Flower-class corvettes had their origins in a sketch design by the Smiths Dock Company which was based on their whaling ship Southern Pride, but lengthened by 9.1 metres (30 ft). Many ships of the class were modified while they were under construction, or as the opportunity presented itself during service.
Mallow had a overall length of 205 feet (62.5 m), a beam of 33 ft 2 in (10.11 m), and a draught of 13 ft 7 in (4.14 m) extending to 15 ft 9 in (4.80 m) at deep load. While her standard displacement was 925 tonnes (910 long tons), she displaced 1,170 tonnes (1,150 long tons) at deep load. She had a crew of 85 officers and enlisted men. She was powered using steam created by two Admiralty three-drum boilers driving a single 4-cylinder triple-expansion steam engine that generated 2,750 indicated horsepower (2,050 kW). The engine drove a single propellor and she could reach a top speed of 16.5 knots (30.6 km/h; 19.0 mph). She carried 230 tonnes (230 long tons) of fuel oil, which gave her a range of 3,450 nautical miles (6,390 km; 3,970 mi) at 12 knots (22 km/h; 14 mph).
The ship was armed with a single 4-inch (100 mm) Mk IX naval gun, two depth charge throwers and two depth charge rails, and could carry 40 depth charges. Ships of the class were also initially equipped with two twin 0.5-inch (12.7 mm) machine guns and two twin 0.303-inch (7.7 mm) machine guns. Later in the war, ships of the class received two additional depth charge throwers and their capacity was increased to 70 depth charges. The machine guns proved inadequate as air defence weapons, and were replaced by heavier guns. In 1944, Mallow' anti-aircraft armament included a total of six 20 mm (0.79 in) Oerlikon cannons, and one 2-pounder (40 mm (1.6 in)) "pom-pom" autocannon. This was intended to better meet the higher air threat in the Mediterranean Sea. She was also equipped with rocket rails fitted to the gun shield of the 4-inch gun, a forward-firing anti-submarine Hedgehog fitted aft of the main gun, and had a Type 271 radar fitted on the rear of her bridge. By 1945, Mallow's armament had been further enhanced with two 6-pounder Hotchkiss mounts.
Mallow was built by the firm of Harland and Wolff at Belfast, Northern Ireland under shipyard number 1065, and was ordered on 19 September 1939, laid down on 14 November 1939, launched on 22 May 1940, and commissioned on 2 July 1940. She was allocated the pennant number K81, and her first captain was Lieutenant Commander William Brown Piggott.
Mallow was quickly put into service as a convoy escort from July 1940 onwards, her first convoy was OB 187 which departed Liverpool on 21 July. During the balance of 1940 she was engaged as an escort for 24 convoys as they left from or arrived at Liverpool. On 17 Nov 1940, she picked up 18 survivors from the British merchantman Saint Germain which was torpedoed and sunk by the German U-boat U-137 north-north-west of Tory Island, off the north coast of Ireland. During 1941, she escorted 22 convoys to and from Liverpool, as well as three that departed from Milford Haven in Wales. On 1 July 1941, Lieutenant William Robert Boyce Noall took command of Mallow. In September, Mallow was part of the escort for convoy HG 75 from Gibraltar to Liverpool which lost four merchantmen to German U-boats, including three sunk by German U-boat U-564 captained by Oberleutnant zur See (First Lieutenant) Reinhard Suhren. In October 1941 she was serving with the 37th Escort Group based in Liverpool, along with two sloops and seven other corvettes. On 19 Oct 1941, Mallow and the Shoreham-class sloop HMS Rochester sank the German U-boat U-204 near Tangier, using depth charges.
During 1942, Mallow escorted 15 convoys, again mainly to and from Liverpool, and escorted the same number in 1943, remaining with the 37th Escort Group covering the United Kingdom – Mediterranean and Sierra Leone convoy routes. On 10 May 1943, Temporary Acting Lieutenant Commander Harold Thomas Stewart Clouston assumed command of Mallow. In December 1943, Mallow was not listed as active on the Navy List.
On 11 January 1944, Mallow was transferred to the Royal Yugoslav Navy-in-exile and renamed Nada. She sailed with a nucleus crew in convoy OS 68/KMS 42 which departed Liverpool on 12 February and arrived at Gibraltar on 25 February. Nada then commenced escort duties in May, conducting a total of 17 convoy escorts between Gibraltar and Port Said to October. During her final escort of 1944, she was detached from convoy KMS 66 as her crew was not considered "politically reliable" because they were not aligned with Josip Broz Tito's Partisan forces. She is recorded as participating in one escort in early February 1945. After the conclusion of the war, Nada was taken over by the fledgling Yugoslav Navy and renamed Partizanka. In 1949, she was returned to the Royal Navy and reverted to HMS Mallow. The requirement to return Partizanka was a painful blow to the Yugoslavs, as she was one of few modern warships in service with them at the time. On 28 October 1949, Mallow was transferred to the Egyptian Navy where she served as El Sudan. She remained in service until 1975, latterly in a training role, and was discarded in that year.