HMS Launceston Castle (F397): A Kill Claimed, Then Fifty Years Later Disproved

Laid Down at Blyth

HMS Launceston Castle was ordered on 19 January 1943, one of fourteen Castle-class corvettes, and laid down at Blyth Shipbuilding's yard in Northumberland on 27 May that year, launched on 27 November 1943 and completed on 20 June 1944, the first Royal Navy ship to carry the name.

She carried the pennant number K397, later changed to F397 in 1948, and was armed with a 4-inch gun, Oerlikon cannon and a Squid anti-submarine mortar, a remarkably capable submarine-hunting fit packed into a hull measuring just 252 feet.

Hunting U-boats in the Western Approaches

HMS Launceston Castle joined Escort Group B4, later redesignated the 30th Escort Group, under the command of Commander Denys Rayner, and carried out convoy escort and anti-submarine patrol duties across the Western Approaches, the English Channel and the North Sea, exactly the kind of relentless, unglamorous work that defined so much of the corvette fleet's contribution to the Battle of the Atlantic.

Rayner is worth a detour, because he was not a regular officer at all. Denys Arthur Rayner was RNVR, a peacetime amateur commissioned out of the reserve, and he finished the war with a DSC and Bar having commanded an anti-submarine trawler, two classes of corvette and three classes of destroyer. Just after Christmas 1942 he was given an escort group of his own, in the old destroyer HMS Shikari, which made him one of the first reservists in the Royal Navy to be handed one.

He had already been sunk once by then. In October 1943 he took command of the destroyer HMS Warwick, and on 20 February 1944, off Trevose Head on the north Cornish coast, U-413 put a torpedo into her. Ninety of her ship's company were killed. Rayner was pulled out of the water by a steam trawler named Lady Luck, which is a detail nobody would dare invent, and was back at sea in command of a group working the Channel in time for the invasion. Launceston Castle joined him after that.

What he did next is the good part. He wrote the war up in 1955 as Escort: The Battle of the Atlantic, still one of the best first-hand accounts of the job there is, with an introduction by the official historian Stephen Roskill. Then he farmed for a while, and then he started designing small boats in glass fibre. In May 1963 he opened a factory in Hambledon Road, Waterlooville, a few miles inland from Portsmouth, trading as Westerly Marine Construction, and drew the twin-keel Westerly 22.

The twin keels were the whole idea. They let a small cruising yacht take the ground upright in a drying creek on a falling tide, which meant an ordinary family could keep a proper sea-going boat somewhere cheap instead of in deep water at deep-water prices. Westerly grew on the back of it into one of the most successful British yacht builders of the next twenty-five years. Rayner died in January 1967, five weeks short of fifty-nine. There is a serious argument that the man who took Launceston Castle's group to sea did more for British sailing after the war than during it.

A Kill That Wasn't

HMS Launceston Castle took part in a coordinated attack with her sister ships against a sonar contact south of Ireland on 11 November 1944, a barrage that brought a slick of oil and a large air bubble to the surface, seemingly conclusive evidence at the time, and was credited with sinking the German submarine U-1200.

It was a claim that stood unchallenged for well over half a century, until 1999, when the actual wreck of U-1200 was discovered south-east of Start Point in Devon, a location entirely inconsistent with the site of the 30th Escort Group's attack.

The wreck lay some 270 nautical miles from where the corvettes had opened fire, in the English Channel rather than the Atlantic approaches. The U-boat loss researcher Axel Niestlé formally documented the discrepancy in December 2013, dating U-1200's actual loss to on or about 12 November, the day after the 30th Escort Group's attack had already been logged as a kill.

No Allied attack is known to have taken place anywhere near where U-1200 actually went down, and to this day nobody has established what sank her. All 53 of her crew were lost, an unsolved mystery quietly sitting behind what had looked, for decades, like a tidy piece of wartime record-keeping.

The submarine at the middle of all this had done nothing whatever. U-1200 was a Type VIIC, commissioned on 5 January 1944 under Oberleutnant Hinrich Mangels, and she made exactly one war patrol. She sank no ships and damaged none. Every man aboard died, on or about 12 November 1944, in a position where no Allied ship is known to have attacked anything at all.

The four that thought they had her were Launceston Castle, Pevensey Castle, Portchester Castle and Kenilworth Castle, four Castle-class corvettes working a single contact together, which is exactly what a support group was built to do. Whatever they hit that day, the oil and the air bubble were convincing enough at the time, and that is the difficulty in a sentence. A group commander in 1944 was working from an echo, a stopwatch and whatever floated up afterwards. Oil comes off wrecks that have been on the bottom for years, and a U-boat under attack could blow oil and rubbish out through a torpedo tube on purpose for precisely that reason.

It was also the wrong end of the war for certainty. By late 1944 what was left of the U-boat arm had been pushed off the ocean and into British coastal water, where a schnorkel-fitted boat could sit on the bottom in a tideway among wrecks and rock and be effectively invisible to the sonar of the day. That change, and what it did to the hunting, is set out in the article on HMS Grenadier (T334). The wonder is not that one kill in November 1944 was credited to the wrong ships. It is that so many of the others were right.

The precise cause of U-1200's loss remains uncertain even today, and it now appears the group's attack that November day struck something other than the submarine they had believed they sunk, a properly fascinating and rather humbling reminder of just how difficult it was to confirm a kill in the chaotic, sound-only world of wartime anti-submarine warfare, and how easily a confident claim could outlive its own accuracy by decades.

Air-Sea Rescue and a Coronation Review

HMS Launceston Castle spent July to October 1945 on air-sea rescue duties operating out of Freetown in West Africa, supporting American troop repatriation flights as the war wound down, before entering reserve at Devonport in 1947.

She returned to active service as an Air Training Target Ship with the 2nd Training Squadron following refits at Bristol and Falmouth, took part in the 1953 Coronation Fleet Review, and carried out search operations for missing RAF aircraft in January 1955, including a lost Fairey Firefly.

In February 1957 she assisted the merchant vessel Holdernore in gale conditions in the Inner Hebrides, a useful piece of practical seamanship late in her career.

A Quiet End

HMS Launceston Castle was sold for scrap in 1959, arriving at J. A. White's yard at St David's on the Forth for breaking up on 3 August that year, closing out the career of a corvette whose most famous wartime achievement turned out, after half a century of hindsight, to have been rather less certain than it had once seemed, a particularly interesting historical footnote for a ship whose day-to-day service was otherwise the standard, steady stuff of convoy protection.