The Corvette was reborn in the RN out of desperation.
The start of WW2 found the Royal Navy horribly unprepared for a resumption of a U-Boat war, and in particular one in which the U-Boat was no longer a coast hugging gun and torpedo boat with a limited ability to submerge. The submarine was coming of age, it could cruise underwater for long periods, surfacing under cover of darkness to recharge. Range, although still limited, was about to get a terrifying boost with the capture of the French ports, the Atlantic was now wide open to the U-Boats, the RN could not even provide basic escort protection across it.
An early re-introduction of the convoy system, so bitterly contested by the RN in WW1, helped considerably, but the U-Boat tactic of the Wolf Pack had been designed to counter it and as more boats became available the Admiralty began to see just what it had originally feared about convoys: they were just big targets.
British ship building had declined since the First World War, the capacity was simply no longer there to turn out warships in the same numbers, Dalmuir for instance, a purpose built modern yard which had turned out battleships and aircraft carriers, had closed in 1931. Increasing losses of merchantmen meant that they too had to be built, even at the expense of warships.
Nowhere was this lack of capacity more obvious and crippling than in turbine engined ships. Though it may seem madness the dockyards were fixed in traditional practises, one of which was that the turbines were built with the ship, by the ship builder, even the exigencies of war could not persuade the breach of tradition to allow turbine construction to be outsourced.
It would be unfair to imply this was all down to the ship builders, they had expanded capacity in WW1 only to see the government ignore them afterwards, causing unemployment and bankruptcy when there were no longer orders to pay for the extended yards. Many feared a repeat of this at the end of the current crises.
In 1938 although the talk was of peace it had become obvious that Nazi Germany was massively re-arming and U-Boats were now openly being built in defiance of the treaty and rolling off the slipways at an alarming rate. Typically though the powers that were looked to the previous war and planned to fight the next the same way. In WW1 the greatest losses to the U-Boat had occurred in coastal waters, due to the short range of U-Boats and because the Atlantic is a big ocean to look for ships in, but their arrival and departure points are well known.
So the need was perceived for coastal escorts, and lots of them. The P type Patrol Boat used in WW1 could not be produced now in sufficient time or quantity, but experience had shown the P Class' high speed was redundant when it came to shepherding slow merchant ships up and down the coast to muster points, so it was reasoned a non-turbine vessel could be employed, a long look was taken at the aborted Kil Class, an escort proposed in WW1 based on an existing merchant ship design which could be produced in non specialist yards, or in the unused capacity of larger yards.
In the event by some forward thinking genius or sheer dumb luck the design that was chosen was not that of a coaster, but of a deep sea whaler that had shown it was up to the ravages of the Atlantic Winter: Smith's shipbuilders Southern Pride.
The Flower Class was adopted as the Class name, reflecting the premier escort vessel of WW1, but either through whimsy or some sort of propoganda spoof they were typed not as Sloops, but as Corvettes, which used to be more heavily armed than Sloops, though certainly not in this case!
Incidently both Southern Pride and her sister ship the Southern Gem were armed and operated as Escorts, the Southern Pride was lost June 16 1944, but Southern Gem became the Suderoy VI in 1936 and served as a mine sweeper in the Canadian Navy, surviving the war.
Flower Class Corvette
By no stretch of the imagination was the Flower Class Corvette heavily armed, initially they carried only a single 4" gun, salvaged from obsolete ships, and a couple of machine guns. Her main weapon were the depth charges.
A crew of 90 in a ship originally designed for 28 and a tendency to "roll on wet grass" made living conditions on the ships tantamount to a damp hell; but they proved ideal for the role of coastal escort, tough, economical, could be built in a month in a small yard, the Flower was adopted by the Canadians, the Americans, the Frech and the Belgiums, even the Germans, four captured in build in France were completed and pressed into service with the Kriegsmarine.
Top speed was 16 knots in short sprints, sufficient to charge at a submerged U-Boat, but inadequate to pursue on the surface, the general tactic was to force the submarine to dive and keep it down with depth charges while the escorted ships escaped and more capable Sloops, and later Frigates, were called up to make the kill.
With the fall of France the impetus of the U-Boat war switched to deep water, often beyond the Western Approaches. U-Boats no longer had to risk the dash through the English Channel, or the gruelling long haul up around the Faeroes Gap of the Denmark Strait, under the constant threat of air attack. The need to escort ships deeper into the Atlantic put a huge strain on an already overworked escort fleet and the Flowers were forced to take up the strain.
The Flower Class remained in production throughout the war, despite it's drawbacks, it was also produced abroad, there are many variants to the original design, and in that it is acting as designed: soaking up spare resources. But the basic design remained largely the same, except it was modified with a longer Forecastle to improve sea keeping in the Atlantic, and the Bridge and Charthouse was improved. AA weapons were increased when available, though this was usually just a pom-pom. Originally fitted with mine sweeping gear as well as depth charges this was discarded and allowed 70 depth charges and up to four throwers to be fitted in additional to twin racks deploying astern.
The effectiveness of the Flower was vastly improved with radar. Initially SW1C and SW2C were tried, but these sets were useless against small U-Boat contacts, but in 1943 the 271 became increasingly available in it's distinctive lantern cupola, in good conditions even a periscope could be picked up and the night was no longer the safe hunting ground for the Wolf Pack.
The Flower played as big a part in the defence of this country as the Spitfire, but while the Spitfire was a sleek thoroughbred the Flower was a Junkyard dog.
Flower Class, Original Specification
Originally fitted with minesweeping gear, later
Later fits varied widely, some were converted to full minesweepers (usually the unmodified early ships), most gained extra Oerlikons or machine guns and the forward firing Hedgehog spindle mortar in addition to their original fit. The area of operation often dictated what the ship carried, those involved in the Mediterranean and the Russian convoys had priority. The mast, positioned forward of the Bridge, was moved behind the Bridge in most modified versions.
I have attached a table of British built Flowers at the bottom of this page, this does not include thouse built in Canada and elsewhere.
Most Flowers were sold off post war, though some
saw service as weather ships for a while, although rugged and reliable
they were simply too small to be able to mount modern ASW weapons, and
far too slow, by the war's end submarines could even outrun the Flower
submerged on a snorkel, and faster boats were to come. But if Athens
had it's wooden wall of ships to defend it then in the darkest days
of Britain's need we had the steel wall of Flowers.
Castle Class Corvette
The Castle was an improved Flower Class design proposed by the same builder: Smiths, it had a greater length and beam to improve sea keeping, and a strengthened bow to take the new Squid Anti-Submarine Mortar, otherwise it was essentially the same ship with a single screw reciprocating steam engine.
Smiths also designed a much improved version, the River Class, but the Castle was designed to follow on from the Flower using small yards. 44 were constructed, and another 14 were in build but cancelled. They were poor at manouvering, particularly at low speed which was needed for operation of the Squid and they were not particularly succesful, considered very underpowered and hard to keep on course. But they show a surprising longevity post war despite that.
Engines: 2 x Admiratly 3 drum boilers, 1 x triple expansion reciprocating engine, single shaft, 2750 ihp
Speed 16.5 knots
Range: 9000 miles at 10 knots, 480 tons of oil
Length: 252 ft overall, Beam 36ft 8", Draught 13ft 6"
Displacement: 1060 tons unloaded, 1630 full load.
Armament: 1 x 4" gun, 2 x twin Oerlikon, up to 6 single Oerlikon (but usually only 2), 1 x three barrel 12" Squid, Depth charge rails and throwers with 15 depth charges.
Radar: Type 272 and later 277 on some
Sonar: 144Q and 147B for the Squid.
Cost: (Rushen Castle) £119, 140 14sh 10d (One hundred and Nineteen thousand, one hundred and forty pounds fourteen shillings and ten pence)
Those Castles which survived the war were reclassified as Frigates in 1948 and changed pennant numbers accordingly, however it is unlikely any saw service as frigates, most were probably employed in various auxilliary duties such as wreck and ordanance disposal and colonial guard ships. Four went on to serve as Atlantic weather ships, replacing Flowers which were previously on station, these were the Oakham Castle, Amberley Castle, Rushen Castle and Pevensey Castle.
In 1948 with the penant change to Frigate and the Flowers sold the RN's brief flirtation with the Corvette Class ended. Another ship would appear that could have taken the title of Corvette, the Type 14 Blackwood Class, but instead they were designated as Second Rate Frigates.
HMS St Thomas Castle
The Castle Class were a larger version of the Flower, designed for better sea keeping and to mount the forward firing Squid mortar and it's associated sonars. But the power plant was the same as for the lighter Flower, itself under-powered, and the result was lack lustre performance, although championed still by those who served on them they lacked the manouverablility needed for a good submarine killer.
Although handsome ships the Castle Class like HMS Flint Castle here lacked power for speed and manouverability. The business end of the ship can be seen just aft the forward turret, the triple barrelled Squid Mortar peeking up over it's barbette. Strangely many survived to become Frigates, but that may have been more due to the fact they were so economical to operate.
HMS Empire Shelter, one of two Castles converted to Rescue Ships which operated with convoys.
|Allington Castle||K689||F89||Jun 1944||1958 Scrapped|
|Alnwick Castle||K405||F105||Nov 1944||1958 Scrapped|
|Amberly Castle||K386||F286||Nov 1944||1958 Air Ministry|
|Bamborough Castle||K412||F12||May 1944||1959 Scrapped|
|Barnard Castle||K694||Jan 1945||Empire Shelter, Convoy Rescue 1955 Scrapped|
|Berkeley Castle||K387||F387||Nov 1943||1956 Scrapped|
|Caistor Castle||K690||F690||Sep 1944||1956 Scrapped|
|Carisbrooke Castle||K379||F379||Nov 1943||1958 Scrapped|
|Denbigh Castle||K696||Dec 1944||Feb 1945 Sunk|
|Dumbarton Castle||K388||F388||Feb 1944||1961 Scrapped|
|Farnham Castle||K413||F413||Jan 1945||1960 Scrapped|
|Flint Castle||K383||F383||Dec 1943||1958 Scrapped|
|Gorey Castle||K529||F386||May 1945||1958 Scrapped|
|Guildford Castle||K378||Mar 1944||Sold 1946|
|Hadleigh Castle||K355||F355||Sep 1943||1959 Scrapped|
|Hedingham Castle||K396||May 1944||1944 Canada Navy|
|Hever Castle||K521||Aug 1944||1949 Chinese Navy|
|Hurst Castle||K416||Jun 1944||Sep 1944 Sunk|
|Kenilworth Castle||K420||F420||Nov 1943||1959 Scrapped|
|Knaresborough Castle||K389||F389||Apr 1944||1956 Scrapped|
|Lacaster Castle||K691||F691||Sep 1944||1960 Scrapped|
|Launceston Castle||K397||F397||Jun 1944||1959 Scrapped|
|Leeds Castle||K384||F384||Feb 1944||1958 Scrapped|
|Maiden Castle||K443||Nov 1944||Empire Lifeguard Convoy Rescue 1955 Scrapped|
|Morpeth Castle||K693||F693||Jul 1944||1960 Scrapped|
|Nunnery Castle||K446||Oct 1944||1949 Chinese Navy|
|Oakham Castle||K530||F530||Dec 1944||1958 Air Ministry|
|Oxford Castle||K692||F692||Mar 1944||1960 Scrapped|
|Pevensey Castle||K449||F449||Jun 1944||1958 Air Ministry|
|Pembroke Castle||K450||Jun 1944||1952 Chinese Navy|
|Portchester Castle||K362||F362||Nov 1943||1958 Scrapped|
|Rayleigh Castle||K695||Oct 1944||1962 Scrapped|
|Rising Castle||K398||Jun 1944||1946 Uruguay Navy|
|Rushen Castle||K372||F372||Feb 1944||1958 Air Ministry|
|Sandgate Castle||K373||May 1944||1946 Sold|
|Scarborough Castle||K536||Jan 1945||1945 Sold|
|Sherbourne Castle||K453||Jul 1944||1946 Sold|
|Shrewsbury Castle||K474||Aug 1943||1943 Norwegian Navy|
|Tamworth Castle||K393||Jul 1944||1946 French Navy|
|Tintagel Castle||K399||F399||Apr 1944||1958 Scrapped|
|Totnes Castle||K447||Sep 1944||1959 Scrapped|
|Walmer Castle||K460||Sep 1944||1946 Sold|
|Wolvesey Castle||K461||Jun 1944||1947 Sold|
|York Castle||K537||Feb 1945||1955 Scrapped|
|Corvette Name||Pennant No.||Shipyard Origin||Date Of Commission||Fate|
|Abelia||K184||Harland & Wolff||28.11.40||Norway as Andenes|
|Acanthus||K01||Ailsa||26.5.41||To the Free French as Aconite|
|Alisma||K185||Harland & Wolff||17.12.40|
|Alyssum||K100||Brown:Kincaid||3.3.41||To the Free
French as Alysse
Sunk 9 Feb 1942
|Amaranthus||K17||Fleming & Fergusun||17.10.40|
|Anchusa||K186||Harland & Wolff||15.1.41|
|Arabis||K73||Harland & Wolff||14.2.40||To the USN as Saucy|
|Arbutus||K86||Blyth:Clark||5.6.40||Sunk 5 Feb 1942|
|Armeria||K187||Harland & Wolff||16.1.41|
|Arrowhead||K145||Marine Industries, Quebec||22.11.1940||To Canada as Arrowhead|
|Asphodel||K56||Brown:Kincaid||25.5.40||Sunk 10 Mar 1944|
|Aster||K188||Harland & Wolff||12.2.40|
|Auricula||K12||Brown:Kincaid||14.11.40||Sunk 6 May 1942|
|Azalea||K25||C.W. & G.:Holmes||8.7.40|
|Begonia||K66||C.W. & G.:Holmes||18.9.40||To the USN as Impulse|
|Bergamot||K189||Harland & Wolff||15.2.41|
|Bittersweet||K182||Marine Industries, Quebec||23.1.1941||To Canada as Bittersweet|
|Bluebell||K80||Fleming & Ferguson||24.4.40||Sunk 17 Feb 1945|
|Bryony||K192||Harland & Wolff||04.06.42|
|Burdock||K126||Crown: N.E. Marine||14.12.40|
|Buttercup||K193||Harland & Wolff||10.4.41||To Norway as Buttercup|
|Calendula||K28||Harland & Wolff||21.3.40||To the USN as Ready|
|Camellia||K31||Harland & Wolff||4.5.40|
|Campanula||K18||Fleming & Ferguson||23.5.40|
|Candytuft||K09||Grangemouth:N.E.Marine||8.7.40||To the USN as Tenacity|
|Carnation||K00||Grangemouth:N.E.Marine||3.9.40||To the Netherlands as Frisco|
|Chrysanthemum||K195||Harland & Wolff||11.4.41||To the Free French as Commandant Drogou|
|Clarkia||K88||Harland & Wolff||7.3.40|
|Clematis||K36||Hill:Richardson W. C.||22.4.40|
|Clover||K134||Fleming & Ferguson||30.1.41|
|Columbine||K94||Hill:Richardson W. C.||13.8.40|
|Convolvulus||K45||Hill:Richardson W. C.||21.9.40|
|Coreopsis||K32||Inglis:Kincaid||23.5.40||To Greece as Kriezis|
|Coriander||K183||Hall, Russell & Co||16.9.1941||To the Free French as Commandant Detroyat|
|Cowslip||K196||Harland & Wolff||23.5.40|
|Eglantine||K197||Harland & Wolff||27.8.41||To Norway as Eglantine|
|Erica||K50||Harland & Wolff||18.6.40||Sunk 9 Feb 1943|
|Eyebright||K150||Canadian Vickers||26.11.1940||To Canada as Eyebright|
|Fennel||K194||Marine Industries, Quebec||15.5.1941||To Canada as Fennel|
|Fleur de Lys||K122||Smiths Dock||26.8.1940||Sunk 14 Oct 1941|
|Freesia||K43||Harland & Wolff||3.10.40|
|Fritillary||K199||Harland & Wolff||22.7.41|
|Gardenia||K99||Simons||10.4.40||Sunk 9 Nov 1942|
|Genista||K200||Harland & Wolff||24.7.41|
|Gentian||K90||Harland & Wolff||6.8.40|
|Gladiolus||K34||Smiths Dock||24.1.40||Sunk 17 Oct 1941|
|Gloxinia||K22||Harland & Wolff||2.7.40|
|Godetia(i)||K72||Smiths Dock||8.5.40||Sunk 6 Sep 1940|
|Heartsease||K15||Harland & Wolff||20.4.40||To the USN as Courage|
|Heather||K69||Harland & Wolff||17.9.40|
|Heliotrope||K03||Crown:N.E.Marine||5.6.40||To the USN as Surprise|
|Hepatica||K159||Davie Shipbuilding, Quebec||15.5.1941||To Canada as Hepatica|
|Hibiscus||K24||Harland & Wolff||6.4.40||To USN as Spry|
|Hollyhock||K64||Crown: N.E.Marine||19.8.40||Sunk 9 Apr 1942|
|Hyacinth||K84||Harland & Wolff||19.8.40||To Greece as Apostolis|
|Jonquil||K68||Fleming & Ferguson||9.7.40|
|Kingcup||K33||Harland & Wolff||31.10.40|
|Larkspur||K82||Fleming & Ferguson||5.9.40||To the USN as Fury|
|Lotus (i)||K93||Hall:Ailsa||17.1.42||To the Free French as Commandant d'Estienne d'Orves|
|Mallow||K81||Harland & Wolff||22.5.40||To Yugoslavia as Nada|
|Marigold||K87||Hall Russell||4.9.40||Sunk 9 Dec 1942|
|Mayflower||K191||Canadian Vickers||15.5.1941||To Canada as Mayflower|
|Meadowsweet||K144||Hill:Richardson W. C.||28.3.42|
|Mimosa||K11||Hill:Richardson W.C.||18.1.42||To the Free
French as Mimosa
Sunkk 9 Jun 1942
|Monkshood||K207||Fleming & Ferguson||17.4.41|
|Montbretia||K208||Fleming & Ferguson||27.5.41||To Norway as Montbretia|
|Orchis||K76||Harland & Wolff||15.10.40||Sunk 21 Aug 1944|
|Peony||K40||Harland & Wolff||4.6.40||To Greece as Sakhtouris|
|Periwinkle||K55||Harland & Wolff||24.2.40|
|Picotee||K63||Harland & Wolff||19.7.40||Sunk 12 Aug 1941|
|Pimpernel||K71||Harland & Wolff||16.11.40|
|Polyanthus||K47||Robb:Kincaid||30.11.40||Sunk 21 Sep 1943|
|Potentilla||K214||Simons||18.12.41||To Norway as Potentilla|
|Renonculus||K117||Simons||25.6.41||To the Free French as Renoncule|
|Rhododendron||K78||Harland & Wolff||2.9.40|
|Rockrose||K51||Hill:Richardson W. G.||26.7.41|
|Rose||K102||Simons||22.9.41||To Norway as Rose|
|Salvia||K97||Simons||6.8.40||Sunk 24 Dec 1942|
|Samphire||K128||Smiths Dock||14.4.41||Sunk 30 Jan 1943|
|Saxifrage||K04||Hill:Richardson W. C.||24.10.41|
|Snapdragon||K10||Simons||3.9.40||Sunk 19 Dec 1942|
|Snowberry||K166||Davie Shipbuilding, Quebec||26.11.1940||To Canada as Snowberry|
|Spikenard||K198||Davie Shipbuilding, Quebec||15 May 1941||To Canada
Sunk 11 Feb 1942
|Sundew||K57||Lewis||28.5.41||To Free French as Roselys|
|Tamarisk||K216||Fleming & Ferguson||28.7.41||To Greece as Tompazis|
|Trillium||K172||Canadian Vickers ltd||31 Oct 1940||To Canada as Trillium|
|Veronica||K37||Smiths Dock||17.10.40||To USN as Temptress|
|Vervain||K190||Harland & Wolff||12.3.41||Sunk 20 Feb 1945|
|Windflower||K155||Davie Shipbuilding, Quebec||4.7.1940 (Launch, not commissioned)||To Canada
Sunk 12 Dec 1941
|Zinnia||K98||Smiths Dock||28.11.40||Sunk 23 Aug 1941|