The Flower-class corvetteGardiner and Chesneau 1980, p. 62.(reproduction with introduction by Antony Preston), Jane's Fighting Ships of World War II, New Jersey: Random House, 1996, , page 68.United States Navy Warship Identification Manual (NAVPERS 10796) (also referred to as the Gladiolus class after the lead ship)Fitzsimons, Bernard, ed. The Illustrated Encyclopedia of 20th Century Weapons & Warfare (London: Phoebus, 1978), Volume 11, pp. 1137–42. was a British class of 294 corvettes used during World War II by the Allied navies particularly as anti-submarine convoy escorts in the Battle of the Atlantic. Royal Navy ships of this class were named after flowers.
Most served during World War II with the Royal Navy (RN) and Royal Canadian Navy (RCN). Several ships built largely in Canada were transferred from the RN to the United States Navy (USN) under the lend-lease programme, seeing service in both navies. Some corvettes transferred to the USN were crewed by the US Coast Guard.
The vessels serving with the US Navy were known as Temptress- and Action-class patrol gunboats. Other Flower-class corvettes served with the Free French Naval Forces, the Royal Netherlands Navy, the Royal Norwegian Navy, the Royal Indian Navy, the Royal Hellenic Navy, the Royal New Zealand Navy, the Royal Yugoslav Navy, and, immediately after the war, the South African Navy.
After World War II many surplus Flower-class vessels were used in other navies, or for civilian use. is the only member of the class preserved as a museum ship.
Class designation The months leading up to World War II saw the RN return to the concept of a small escort warship being used in the shipping protection role. The Flower class was based on the design of Southern Pride, a whale-catcher, and were labelled "corvettes", restoring the title for the RN, although the Flower class has no connection with pre-1877 types.
There are two distinct groups of vessels in this class: the original Flower class, 225 vessels ordered during the 1939 and 1940 building programmes; and the modified Flower class, which followed with a further 69 vessels ordered from 1940 onward. The modified Flowers were slightly larger and better armed.
Flower-class vessels, of original and modified design, in USN service were called Temptress- and Action-class gunboats. They carried the hull classification symbol PG ("patrol gunboat").
Design
In early 1939, with the risk of war with Nazi Germany increasing, it was clear to the Royal Navy that it needed more escort ships to counter the threat from Kriegsmarine U-boats. A particular concern was the need to protect shipping off the east coast of Britain. What was needed was something larger and faster than trawlers, but still cheap enough to be built in large numbers, preferably at small merchant shipyards, as larger yards were already busy. To meet this requirement, the Smiths Dock Company of South Bank -on-Tees, a specialist in the design and build of fishing vessels, offered a development of its 700-ton, whaler (whale catcher) Southern Pride.Brown 2007, pp. 41–43.Lambert and Brown 2008, p. 3.
They were intended as small convoy escort ships that could be produced quickly and cheaply in large numbers. Despite naval planners' intentions that they be deployed for coastal convoys, their long range meant that they became the mainstay of Mid-Ocean Escort Force convoy protection during the first half of the war.
The Flower class became an essential resource for North Atlantic convoy protection until larger vessels such as destroyer escorts and frigates could be produced in sufficient quantities. The simple design of the Flower class using parts and techniques (scantlings) common to merchant shipping meant they could be constructed in small commercial shipyards all over the United Kingdom and Canada, where larger (or more sophisticated) warshipsCanadian yards, for instance, could not build destroyer hulls. could not be built. The use of commercial triple expansion machinery instead of steam turbines meant the largely Royal Naval Reserve and Royal Naval Volunteer Reserve crews that were manning the corvettes would be familiar with their operation.
Flower-class vessels were slow for a warship, with maximum speed of . They were also very lightly armed as they were intended solely for anti-submarine warfare; many of the RCN's original Flower-class ships were initially fitted with minesweeping equipment, while virtually all of the modified Flowers were fitted with a limited anti-aircraft capability. The original Flowers had the standard RN layout, consisting of a raised forecastle, a well deck, then the bridge or wheelhouse and a continuous deck running aft. The crew quarters were in the forecastle while the galley was at the rear, making for poor messing arrangements.Brown D K, Nelson to Vanguard
The modified Flowers saw the forecastle extended aft past the bridge to the aft end of the funnel, a variation known as the "long forecastle" design. Apart from providing a very useful space where the whole crew could gather out of the weather, the added weight improved the ships' stability and speed and was applied to a number of the original Flower-class vessels during the mid and latter years of the war.
The original Flowers had a mast located immediately forward the bridge, a notable exception to naval practice at that time. The modified Flowers saw the mast returned to the normal position immediately aft of the bridge; this does not seem to have been done in all of the modified builds or conversions of the original vessels. A cruiser stern finished the appearance for all vessels in the class.
Orders
The RN ordered 145 Flower-class corvettes in 1939, the first 26 on 25 July with a further batch of 30 on 31 August, all under the 1939 Pre-War Programme. Following the outbreak of World War II, the British Admiralty ordered another 20 on 19 September (all from Harland & Wolff) under the 1939 War Programme. This was followed by an order for a further ten Flower-class corvettes from other British shipbuilders two days later. Another 18 were ordered on 12 December and two on 15 December, again from British shipbuilders. In January 1940, the RN ordered the last ten vessels under the 1939 War Programme from Canadian shipbuilders.
By the end of January 1940, 116 ships were building or on order to this initial design. The ten vessels ordered from Canadian shipbuilders were transferred to the RCN upon completion. Another four vessels were ordered at Smiths Dock Company for the French Navy, the first ship being completed for the Free French Naval Forces in mid-1940 and the other three being taken over by the RN. Another 31 Flowers were ordered by the RN under the 1940 War Programme but six of these (ordered from Harland & Wolff) were cancelled on 23 January 1941.
The RN ordered 27 modified Flower-class corvettes under the 1941 and 1942 War Programmes. British shipbuilders were contracted to build seven of these vessels under the 1941 Programme and five vessels under the 1942 Programme; two vessels (one from each year's Programme) were later cancelled. The RN ordered fifteen modified Flowers from Canadian shipyards under the 1941 programme; eight of these were transferred to the USN under reverse Lend-Lease.
The RCN ordered seventy original and 34 modified Flower-class vessels from Canadian shipbuilders. The Canadian shipbuilders also built seven original Flowers ordered by the USN, which were transferred to the RN under the Lend-Lease Programme upon completion, because wartime shipbuilding production in the United States had reached the level where the USN could dispense with vessels it had ordered in Canada. The RCN vessels had several design variations from their RN counterparts: the "bandstand", where the aft pom-pom gun was mounted, was moved to the rear of the superstructure; the galley was also moved forward, immediately abaft the engine room.
Shortly after the outbreak of war the French Navy ordered 18 Flower-class vessels, 12 from UK yards, two from Ateliers et Chantiers de France at Dunkirk and four from Ateliers et Chantiers de Penhoët at Saint-Nazaire.Le Masson 1969, pp. 27–28Le Masson 1969, pp. 26, 28. The two At. & Ch. de France ships are listed as "cancelled" but the four Penhoët ships were under construction at the time of the Fall of France and were seized by Nazi Germany.Le Masson 1969, p. 28 Three were completed for Kriegsmarine service and commissioned in 1943–44 as the Patrouillenboot Ausland patrol ships.
Armament
The original Flower class were fitted with a 4-inch (102 mm) gun on the bow, depth charge racks carrying 40 charges on the stern, a minesweeping winch and a 2-pounder (40 mm) pom-pom gun on a "bandstand" over the engine room. Due to shortages, a pair of Lewis guns or quadruple Vickers HMG was sometimes substituted for the pom-pom, which would have left the ship very vulnerable to aircraft attack in its envisaged role of coastal convoy escort and patrol in the North Sea.
The long-range endurance of the vessels, coupled with early war-time shortages of larger escort warships, saw Flowers assigned to trans-Atlantic convoy escort where Luftwaffe aircraft were rarely encountered. Vessels assigned to the Mediterranean Sea usually had more anti-aircraft guns fitted. Underwater detection capability was provided by a fixed ASDIC dome. This was later modified to be retractable. Subsequent inventions such as the High Frequency Radio Direction Finder (Huff-Duff) were later added, along with radar systems, such as the Type 271, which proved particularly effective in low-visibility conditions in the North Atlantic.
The Flower class were designed for inshore patrol and harbour anti-submarine defence and many required minor modifications when the Allied navies began to use them as trans-Atlantic convoy escorts. These small warships could be supported by any small dockyard or naval station, so many ships came to have a variety of weapons systems and design modifications depending upon when and where they were refitted. There is really no such thing as a 'standard Flower-class corvette'
Several of the major changes that vessels in the class underwent are indicated below, in a typical chronological order: Original twin mast configuration changed to single mast in front of the bridge, then moved behind the bridge for improved visibility. Heavy minesweeping gear removed for deep-sea escort work and to improve range. Galley relocated from the stern to midships. Extra depth charge storage racks were fitted at the stern. Later, more depth charges stowed along walkways. Hedgehog fitted to enable remote attacks while keeping ASDIC contact. Surface radar fitted in a "lantern" housing on the bridge. Forecastle lengthened to midships to provide more accommodation and better seaworthiness. Several vessels were given a "three-quarters length" extension. Increased flare at the bow. This and the above modification created the modified Flower design for subsequent orders. Various changes to the bridge, typically lowering and lengthening it. Enclosed compass house removed. Extra twin Lewis guns mounted on the bridge or engine room roof. Oerlikon 20 mm cannons fitted, usually two on the bridge wings but sometimes as many as six spread out along the engine-room roof, depending on the theatre of operations.