HMS Fleetwood (F47): The Sloop That Sank Two U-Boats a World Apart

Devonport-Built

HMS Fleetwood was ordered on 1 March 1935 and built at Devonport Dockyard, laid down on 14 August 1935, launched on 24 March 1936, and completed on 19 November that year, a Grimsby-class sloop measuring 266 feet 3 inches in length and displacing 990 tons standard, rising to 1,355 tons at full load.

Her geared steam turbines produced 2,000 shaft horsepower for a modest top speed of 16.5 knots, though she carried an impressive range of 6,000 nautical miles at cruising speed, exactly the kind of endurance needed for long overseas postings.

Her modest speed was not an oversight; it was written into her by treaty lawyers. Under the naval limitation agreements of the period, a warship of under 2,000 tons standard displacement, with no gun larger than 6.1 inches, no more than four guns above 3 inches, and a maximum speed of not more than 20 knots, did not count against a country's destroyer tonnage at all. Britain had proposed that exemption itself, and then used it exactly as intended: sloops like Fleetwood were deliberately built slow, so that the Royal Navy could have as many escorts as it liked without any of them appearing on the balance sheet. It was a sensible piece of diplomacy in 1935. In 1940 it meant that a surfaced Type VII U-boat, good for seventeen knots, could simply drive away from her.

Her original armament included four 4-inch guns in twin mounts, saluting guns and a machine gun, along with two depth charge throwers, two rails and 40 depth charges. Her pennant number was not actually painted on her hull until September 1939, initially recorded as U47 before later references to F47 during the war's reclassification of escort vessel pennant prefixes.

HMS Fleetwood served as trials ship for her new armament following commissioning, visiting Gibraltar, Tangier and Cartagena, before arriving at Aden on 27 March 1938 for Red Sea station duties, a fairly typical peacetime deployment pattern for a sloop of her type.

Norway and the East Coast Convoys

HMS Fleetwood was recalled following Germany's invasion of Poland, arriving at Portland on 11 October 1939 for East Coast convoy escort duty.

During the Norwegian Campaign in April and May 1940, she provided anti-aircraft cover at Åndalsnes and Molde, two of the ports through which British forces attempted, ultimately unsuccessfully, to support Norwegian resistance to the German invasion, and towed the damaged HMS Pelican to safety at Lerwick, while also helping evacuate 340 troops during the difficult withdrawal from Norway that followed.

HMS Fleetwood underwent a significant refit at Middlesbrough in 1941, receiving radar and improved anti-aircraft armament, and by 1943 had been further upgraded with Oerlikon 20mm cannon and a Hedgehog anti-submarine mortar, upgrades that transformed her from a fairly modest interwar sloop into a remarkably capable anti-submarine escort.

What both of her kills have in common is the thing that actually won the Battle of the Atlantic, and it is easy to miss because it is in the first line of each account. An aircraft found and damaged the submarine; a surface ship then arrived and finished it. Neither could reliably do it alone. An aircraft could search enormous areas and attack without warning, but it could not stay, could not hold a contact underwater and usually could not confirm a kill; a ship could hold a submerged boat with asdic for hours and depth-charge it methodically, but she had to be told where to go. By 1943 the two had been welded into a single system, with radio links, plotted contacts and a routine for detaching an escort to follow up an aircraft's attack. Fleetwood was detached from her convoy to finish U-528 and was directed onto U-340 in the same way. A slow interwar sloop became lethal the moment somebody else could find the target for her.

Sinking U-528

HMS Fleetwood scored her first confirmed U-boat kill on 11 May 1943, while escorting Convoy OS47. A Halifax patrol aircraft of 58 Squadron RAF had already damaged the German submarine U-528, and HMS Fleetwood, under the command of Commander William Piggott DSC and Bar, RNR, was detached from the convoy to follow up the attack, carrying out a sustained series of depth charge attacks that forced the U-boat to the surface.

She then shelled the crippled submarine alongside the corvette HMS Mignonette, compelling her crew to scuttle rather than continue the fight, and HMS Fleetwood went on to rescue 39 survivors from the water, Mignonette picking up a further six, though eleven of U-528's crew did not make it out alive.

Sinking U-340

HMS Fleetwood, still under Commander Piggott, claimed a second confirmed kill in the small hours of 2 November 1943, near the Strait of Gibraltar. Following an initial attack by a Wellington of 179 Squadron RAF, the German submarine U-340 was located by HMS Fleetwood alongside the destroyers HMS Active and HMS Witherington, who together carried out a depth charge attack that forced the submarine to scuttle, one of her crew killed and the other 48 taken prisoner.

Her surviving crew were taken captive by HMS Fleetwood, marking a truly impressive second submarine kill within the space of six months, both scored under the same commanding officer, for a ship whose interwar career had given little hint of the anti-submarine effectiveness she would go on to demonstrate.

The Wellington that started that second engagement is worth a word, because of what it was carrying. Aircraft could find surfaced U-boats on radar at night perfectly well, and then lose them in the last mile because the radar could not see close in and the crew could not see anything at all. The answer was the Leigh Light: a powerful searchlight slaved to the aircraft, switched on in the final seconds of the attack run, so that the first a U-boat knew of it was a glare and an aircraft already overhead. The first kill by that method came in July 1942, and within a month U-boats in the Bay of Biscay had changed their habits and started surfacing by day instead, on the reasoning that being attacked in daylight was at least survivable. 179 Squadron flew Leigh Light Wellingtons out of Gibraltar and accounted for seven boats in 1943 alone. U-340 was one of them.

It is worth noticing what happened afterwards on both occasions, because it says something about how that war was fought at sea. Fleetwood shelled U-528 until her crew scuttled her, and then stopped and picked thirty-nine of them out of the water; six months later she took forty-eight men off U-340. Eighty-seven German submariners owed their lives to a ship that had spent the previous hours trying to kill them. That was the norm, and it is worth stating plainly, because the single occasion on which a U-boat commander did the opposite, ordering survivors machine-gunned in the water, produced the only war crimes trial of a German naval officer in the entire conflict, described in the article on HMS Fishguard (Y59). Stopping to pick up your enemy was the ordinary thing. Not doing it got a man shot.

The man who did all of it deserves his letters read properly. William Brown Piggott finished the war as Commander, DSC and Bar, OBE, RD, RNR, and the last three of those are the interesting ones. RNR meant the Royal Naval Reserve, which was not the Wavy Navy of civilian volunteers but a standing reserve of professional merchant seamen, men who had spent their working lives in tramp steamers and liners and held certificates to prove it. RD is the Reserve Decoration, awarded for long service in it, so he had been at this a long time before 1939. The DSC and Bar came from Fleetwood.

It is worth sitting with the shape of that. Two U-boats destroyed inside six months, in the Atlantic and off Tangier, by a slow interwar sloop deliberately built to be too slow to catch anything, commanded throughout by a merchant navy officer. A very large proportion of the escort war was fought exactly like that, by professional seamen from the merchant service in ships nobody wanted, and it is the least commemorated part of the whole campaign.

Collisions and Later Service

HMS Fleetwood's war was not entirely without mishap: she collided with the tanker Oil Reliance in June 1942 and with the American patrol boat PC-473 in November 1943, both incidents requiring repairs, an occupational hazard of years spent operating in busy, often poorly lit convoy lanes. She completed her wartime service with Portsmouth Command through to the end of the war.

A Coronation and the End

HMS Fleetwood was laid up in reserve at Hartlepool on 4 August 1945, before being refitted as a radar training ship, a role that put her wartime technical upgrades to further practical use. She took part in the Coronation Fleet Review for Queen Elizabeth II on 15 June 1953, a suitably dignified public appearance for a ship whose wartime record had proven distinguished.

HMS Fleetwood was paid off in December 1958 and sold for scrap in 1959, leaving Portsmouth for breaking up at C.W. Dorkin's yard in Gateshead, closing out the career of a sloop that had accounted for two U-boats and helped save hundreds of lives during the desperate Norwegian campaign of 1940.

One more thing about the class, because its most famous ship is not British. Four Grimsbys were built for Australia, and one of them, HMAS Yarra, fought what is probably the most one-sided surface action of the Pacific war. On the morning of 4 March 1942, about four hundred miles south of Java, she was escorting the last convoy out of the East Indies when her lookout sighted three Japanese heavy cruisers coming up: Atago, Takao and Maya. Each of them mounted ten 8-inch guns. Yarra had three 4-inch.

Her commanding officer, Lieutenant Commander Robert Rankin, ordered her to make smoke to cover the convoy and open fire. There was no version of that morning in which it worked. An 8-inch salvo killed Rankin on his own bridge moments after he had given the order to abandon ship, and Yarra went down shortly after eight o'clock. Five days later the Dutch submarine K11 came across some rafts and took thirteen ratings off them. They were the only survivors from a ship's company of a hundred and fifty-one. Australia later awarded the whole crew the Unit Citation for Gallantry, which is the highest thing the country gives for collective action.

Set that beside Fleetwood and the class comes into focus. The same design, built to the same treaty loophole, deliberately slow and lightly armed because the Admiralty wanted numbers rather than performance: one of them killed two U-boats in the Atlantic under a merchant navy captain and was still afloat in 1958, and another put herself between three heavy cruisers and a convoy and lost a hundred and thirty-eight men doing it. Nobody designs a ship for either of those afternoons. They were built to be cheap and to be numerous, and what they actually did depended entirely on where they happened to be.