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Bluebell / Flower-class file photo [13563]

Flower-class Corvette

CountryUnited Kingdom
Displacement950 tons standard; 1,160 tons full
Length205 feet
Beam33 feet
Draft12 feet
MachineryTriple expansion reciprocating steam engine rated at 2,750ihp
Speed16 knots
Range3,500nm at 12 knots
Armament1x4in BL Mk.IX gun, 1x7.70mm quadruple Vickers .50 machine gun, 2x7.7mm twin Lewis machine guns, 25 depth charges


This article refers to the entire Flower-class; it is not about an individual vessel.

ww2dbaseIn January 1939, Mr. William Reed OBE of Smith's Docks Co. at Middlesbrough, England, United Kingdom was approached by the British Admiralty with a request for a design of a cheap and simple multi-role warship capable of being built in the multitude of small civilian shipyards not usually accustomed to building to naval standards. Smith Docks was highly regarded by the Admiralty because it had designed the Z-class whaler during World War I and was famed for its reputation for the construction of whale-catchers. Reed's resultant design suggestion was based on a larger version of the company's new whaler, Southern Pride, with a number of modifications. The length, for instance, was increased by 30 feet to give a higher speed, and two marine oil-fired boilers were to be fitted as these could be supplied in about 16 weeks instead of water tube boilers which would not be available for at least seven months.

ww2dbaseThe design was rapidly approved and, with war becoming ever more likely, a bulk order was placed with the aim of creating a viable anti-submarine force where none had existed before. The first order, for twenty-six vessels, was soon followed by others, and by the end of 1939 no less than 110 vessels of this kind were under construction at various shipyards around the country (including by some large ones, such as the Harland and Wolff yard at Belfast).

ww2dbaseAt the outbreak of war, some 180 Royal Navy ships were fitted with Asdic, the only known method of underwater submarine detection. Of these, 150 were destroyers, 24 were sloops and six were coastal patrol vessels. The majority of the destroyers were naturally required for fleet work and therefore not available for the protection of mercantile convoys. The sloops turned out to be unable to withstand the normal gales experienced in winter in the north Atlantic, leaving the coastal patrol vessels, later classed as corvettes, with such destroyers as could be spared from other duties, as the back-bone of Britain's escort forces.

ww2dbaseThe Flower-class corvettes, which began to be commissioned in mid-1940, proved to be remarkable little ships with a fantastic ability to keep going in weather in which other ships, such as destroyers, were unable to operate. Their crews however needed strong stomachs, for they rolled excessively in heavy seas and their general habitability was extremely poor. They suffered too from lack of speed - the four-cylinder, triple-expansion engine, as adopted, (simply because patterns for its manufacture were already in existence) was frequently some two or three knots slower than a surfaced U-boat and was well below the minimum of 20 knots required for anti-submarine operations as specified by the naval staff.

ww2dbaseLack of size was another drawback which meant that there was insufficient space aboard to accommodate the more sophisticated anti-submarine weapons and equipment as they were developed. Nevertheless from mid-1941 forward-firing hedgehogs began to be fitted and the number of depth charges carried almost doubled. With enlarged bridges, improved minor weaponry, radar, and an ever-increasing crew the vessels gradually became overloaded and had to carry permanent ballast, to the detriment of freeboard and seaworthiness. By the closing months of World War II the Flower-class corvettes had been improved as much as they could be. But even with up to six 20-millimeter mountings, they were relegated to the sidelines by the new emergency-built vessels now joining the fleet in large numbers.

ww2dbaseDespite their shortcomings the Flower-class corvettes gave sterling service in the Battle of the Atlantic and elsewhere. Although improved escort vessels, such as the Castle-class corvettes and River-class frigates would become available after 1943, the sturdy little Flower-class corvettes continued to provide the backbone of Allied convoy escorts. In total British shipyards would turn out 145 and Canadian shipyards constructed a further 121, many to a modified design. The Canadian-built variants had a greater displacement (1,015 tons standard, 1,240 tons full load) due to a greater typical crew size (96 officers and men) and a slightly heavier weapons load (1x4in BL Mk.IX gun, 2x2pdr 'pom pom' guns, 4x or 6x20mm Oerlikon cannon, 1x Hedgehog depth charge projector, 70 depth charges). Thirty-six Flower-class corvettes were lost in World War II, half to submarines, but they helped kill over fifty U-Boats.

Jane’s Warships of World War II (Harper Collins, 1996)
Jane’s Fighting Ships of World War II (Studia Publishing, 2001)
Corvettes (John Lambert, War Monthly Magazine)
Warships of the Second World War (Purnell’s History of the World Wars Special, 1973)

Last Major Revision: Sep 2011

Flower-class Corvette Interactive Map


Corvette HMS Bluebell underway on the River Tyne, England, United Kingdom, 24 Jun 1942

Flower-class Corvette Operational Timeline

2 Jan 1939 The British Chief of Naval Staff called for a suitable coastal escort vessel capable of being fitted for minesweeping.
27 Feb 1939 The British Admiralty approved William Reed's sketch design for a coastal escort vessel requested during the previous month.
25 Jul 1939 The British Admiralty placed an order for 26 Flower-class corvettes under the 1939-40 Naval Estimates.
25 Jul 1939 The British Royal Navy issued an order to Henry Robb, Limited of Leith, Scotland, United Kingdom for the contruction of a corvette which would later be named Dianthus.
31 Oct 1939 The keel of Dianthus was laid down by Henry Robb, Limited of Leith, Scotland, United Kingdom.
20 Jan 1940 Corvette Trillium was ordered.
20 Feb 1940 The keel for corvette Trillium was laid down.
26 Jun 1940 Corvette Trillium was launched.
9 Jul 1940 HMS Dianthus was launched at Leith, Scotland, United Kingdom.
31 Oct 1940 HMCS Trillium was commissioned into service with Lieutenant Commander Ronald Fraser Harris in command.
20 Jan 1941 Lieutenant Commander Clement Bridgman was named the equipping officer of HMS Dianthus.
17 Mar 1941 HMS Dianthus was commissioned into service with Lieutenant Commander Clement Bridgman in command.
21 Apr 1941 HMCS Trillium rescued 24 survivors of the British merchant ship Empire Endurance, which was sunk between Iceland and Ireland on the previous day by German submarine U-73.
15 Nov 1941 Lieutenant Henry Drummond Campsie was named the commanding officer of HMCS Trillium.
19 Dec 1941 Lieutenant George Edward Gaudreau was named the commanding officer of HMCS Trillium.
26 Feb 1942 Lieutenant Philip Cabell Evans was named the commanding officer of HMCS Trillium.
10 Jun 1942 HMS Dianthus rescued 32 survivors of British merchant ship Empire Clough in the Atlantic Ocean.
5 Aug 1942 HMS Milfoil was launched.
10 Aug 1942 HMS Dianthus rescued survivors of British merchant ships Cape Race, Empire Reindeer, and Oregon in the Atlantic Ocean.
6 Nov 1942 Lieutenant Commander Neil Israel was named the commanding officer of HMS Dianthus.
22 Feb 1943 German submarine U-606 sank British merchant ship Empire Redshank in the North Atlantic; 47 survivors were picked up by HMCS Trillium.
23 Feb 1943 HMS Dianthus rescued 34 survivors of Norwegian merchant ship Glittre in the Atlantic Ocean.
23 Feb 1943 HMCS Trillium rescued 58 survivors of US merchant ship Chattanooga City and 53 survivors of US merchant ship Expositor, both of which were sunk by German submarine U-606 in the North Atlantic on the previous day.
25 Mar 1943 Lieutenant Ralph Marcus Wallace was named the commanding officer of HMCS Trillium.
31 Mar 1943 British corvette HMS Milfoil was recommissioned into the United States Navy as USS Intensity.
18 Apr 1943 Lieutenant Philip Cabell Evans was named the commanding officer of HMCS Trillium.
10 Jun 1943 The work to extend HMCS Trillium's forecastle at Boston Navy Yard, Massachusetts, United States was completed.
31 Aug 1943 Lieutenant Commander Bernard Bowick was named the commanding officer of HMS Dianthus.
22 May 1944 Lieutenant Kenneth Elliot Meredith was named the commanding officer of HMCS Trillium.
5 Mar 1945 Lieutenant James Lyle was named the commanding officer of HMS Dianthus.
25 Jun 1945 HMCS Trillium was decommissioned from service.
27 Jun 1945 HMCS Trillium was transferred to the British Royal Navy.
29 Jun 1945 USS Intensity arrived at Charleston, South Carolina, United States.
3 Oct 1945 USS Intensity was decommissioned from service.

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Visitor Submitted Comments

1. Alex says:
6 Aug 2017 04:53:45 AM

What was the name of the ship that rammed and sank the H.M.H.S. Eburum? (In the Med.?)
A greater tragedy than the Titanic.
2. Commenter identity confirmed David Stubblebine says:
6 Aug 2017 10:37:07 AM

Alex (above):
I cannot find any record that the Eburum ever existed, let alone was sunk. The principal source for the Eburum sinking is an animated YouTube video which seems to be the basis (or perhaps an advertisement) for the Eburum Virtual Sailor Ship-Handling Simulator. The Wikipedia list of Hospital Ships Sunk in World War II (take that for what it is worth) does not list an Eburum or any other ship lost after being rammed by a British corvette. The sinking of the Eburum would appear to be fictional.
3. Anonymous says:
29 Oct 2017 09:37:03 AM

What was the most produced ship during ww2 (type and class)? How many of that specific ship were built? Any relevant, specific, and acccurate details, please include it.

4. Patrick Kavanagh says:
28 Dec 2017 11:07:59 PM

Recently came across a photo of HMS Fritillary K 199 entering the Naval Dockyard in Haulbowline Cobh County Cork Ireland. I am looking for info on this vessel please.
5. Gary Casey says:
25 Feb 2019 10:47:31 PM

My dad servered on the HMCS Agassiz from 1942 to 1946.So Ilike to know how his ship mates where.
6. DAVID says:
27 Nov 2020 08:30:43 AM

Good evening to you, My Father was on a Corvette during world war 2 before 1943 were he was on a HMS Verdun from this date. we have no record before this date but know he was on a Corvette. My Fathers name is Edward Langford Hartley born 1923 in Wolverhampton UK.
We would like to thank you for your help in this matter and look foward to hearing from you in the very near future.
David Hartley
7. Victor Ostuni Jr. says:
19 Jun 2021 10:36:38 AM

My dad ( same name)was on the USS Intensity PG 93 then on an LST 920 for the liberation of the Philippines

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» Dianthus
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Flower-class Corvette Photo Gallery
Corvette HMS Bluebell underway on the River Tyne, England, United Kingdom, 24 Jun 1942

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