Warship – Destroyers and Escorts (Part 4)

USS Intensity, a US-operated 'Flower class' corvette during World War II

In World War I the Royal Navy had received an eventual total of 72 ‘Flower’ class ships that were officially designated as fleet minesweeping sloops. These were built in three subclasses as the ‘Acacia’, ‘Azalea’ and ‘Arabis’ types, and although designed mainly for the fleet minesweeping role soon proved themselves so versatile that they were adapted for other roles such as escort or, in the case of 39 more ships, completed as Q-ships with hidden armament that was designed for the destruction of U-boats lured to the surface by the apparently innocuous appearance of these ‘merchant’ ships. A further 24 ships were built in the ‘24’ class of general-purpose sloops with a central funnel, a dummy bridge aft, and a straight stem and stern to present a double-ended appearance that made it difficult to detect the way the ships were moving at slow speed, especially as effective dazzle painting was employed. These two classes of sloop provided most of the Royal Navy’s coastal escort strength in the second half of World War I, and remained in declining service through the 1920s and 1930s.

New escort ship thinking
In the later 1930s, the apparent inevitability of war with Germany, and with it the concomitant inevitability of a U-boat campaign against the merchant navy fleet on which the UK was wholly reliant, persuaded the Admiralty to reconsider its capabilities for the escort of merchant ship convoys. This process led to orders for 20 fast escort ships for the oceanic role, orders for 56 whale-catcher type vessels for the coastal role, the conversion of old destroyers to the escort task, and the construction of a new class of oceanic escorts as the sloops of the ‘Black Swan’ class. These last were launched from mid-1939, and eventually totalled 37 ships including four for the Royal Indian Navy, with the final five (including another two Indian ships) cancelled in the closing stages of the war. The ships were built in two forms. The ‘Black Swan’ class ships had a displacement of 1,250 tons, an armament of six 4-in (102-mm) anti-aircraft guns in three twin turrets, four 2-pdr guns in a quadruple mounting, and four 0.5-in (12.7-mm) machine-guns in a quadruple mounting or 12 20-mm cannon in six twin mountings, and a speed of 19.25 kt on the 3,600 hp (2685 kW) delivered to two shafts by geared steam turbines. The ‘Modified Black Swan’ class ships had a displacement of 1,350 tons, an armament of six 4-in (102-mm) anti-aircraft guns in three twin turrets and 12 20-mm cannon in six twin mountings, and a speed of 20 kt on the 4,300 hp (3205 kW) delivered to two shafts by geared steam turbines.

Experience soon revealed that the ‘Black Swan’ and ‘Modified Black Swan’ classes offered very useful escort capabilities, but also that they were not necessarily the most cost-effective way to provide these capabilities as they were fairly large vessels built to full warship standards with a geared steam turbine propulsion arrangement. The result was therefore an unattractive combination of high cost and slow production. The Admiralty had already sensed that this would in fact be the case, and in 1939 had ordered another ‘Flower’ class, in this instance of escort corvettes. Eventually 270 of these fine little ships were completed in the UK and Canada for service with the navies of the British empire as well as a number of Allied navies. Based on a whalecatcher design, the ‘Flower’ class corvette was designed for construction to a mercantile (and therefore cheaper and more quickly constructed) standard with a triple-expansion steam propulsion arrangement. The ‘Flower’ class corvettes were produced in two forms. The basic ‘Flower’ class had a displacement of 950 tons, an armament of one 4-in (102-mm) gun, one 2-pdr anti-aircraft gun or four 0.5-in (12.7-mm) machine-guns in a quadruple mounting and four 0.303-in (7.7-mm) machine-guns in two twin mountings, and a speed of 16 kt on the 2,750 hp (2050 kW) delivered to one shaft by a triple-expansion steam engine, while the ‘Modified Flower’ class had a displacement of 980 tons, an armament of one 4-in (102-mm) gun, one 2-pdr anti-aircraft gun, six 20-mm cannon in single mountings and one ‘Hedgehog’ anti-submarine projector, and a speed of 16 kt on the 2,880 hp (2145 kW) delivered to one shaft by a triple-expansion steam engine.

The ‘Flower’ class a vital weapon
The importance of the two subclasses of the ‘Flower’ class to the Allied victory over Germany by May 1945 cannot be overestimated, but from an early date the Admiralty realised that the hull of the ‘Flower’ class ship was slightly too small for the oceanic escort role and therefore ordered the larger and faster ‘River’ class frigates, which were also built to mercantile standards but had a two-shaft propulsion arrangement powered by triple-expansion steam engines. Some 139 of this class were completed in the UK, Australia and Canada for service with the navies of the British empire as well as several Allied navies. The ‘River’ class frigate had a displacement of 1,370 tons, a varied armament of anti-ship and anti-aircraft weapons as well as a Hedgehog anti-submarine projector, and a speed of 20 kt on the 5,500 hp (4100 kW) delivered to two shafts by triple-expansion steam engines. The ‘River’ class frigate was economical to build and certainly effective in operational terms, but its length precluded its construction in many of the smaller yards that had been able to build the corvettes of the ‘Flower’ classes.

The Admiralty thus exploited this underused construction source with the ‘Castle’ class of corvettes, which was built from 1943 and totalled 44 units with a large number of others cancelled at the end of the war. The details of this excellent class included a displacement of 1,010 tons, an armament one 4-in (102-mm) gun, 10 20-mm cannon in two twin and six single mountings and one Squid anti-submarine projector, and a speed of 16.5 kt on the 2,880 hp (2145 kW) delivered to one shaft by a triple-expansion steam engine.

The ‘River’ class was followed into production by the ‘Loch’ and ‘Bay’ classes of general escort and anti-aircraft frigates, which were built from prefabricated assemblies to speed the construction process. Some 56 units of these two classes were completed, with another 54 cancelled late in the war. The details of the ‘Loch’ class included a displacement of 1,435 tons, an armament of one 4-in (102-mm) gun, four 2-pdr anti-aircraft guns in a single mounting, six 20-mm cannon in two twin and two single mountings, and two Squid anti-submarine projectors, and a speed of 20 kt on the 6,500 hp (4845 kW) delivered to two shafts by geared steam turbines or 5,500 hp (4100 kW) delivered to two shafts by triple expansion steam engines. The details of the ‘Bay’ class included a displacement of 1,580 tons, an armament of four 4-in (102-mm) anti-aircraft guns in two twin turrets, four 40-mm anti-aircraft guns in two twin mountings, four 20-mm cannon in two twin mountings and one Hedgehog anti-submarine projector, and a speed of 20 kt on the 6,500 hp (4845 kW) delivered to two shafts by geared steam turbines or 5,500 hp (4100 kW) delivered to two shafts by triple expansion steam engines.

US thinking
When the US became embroiled in World War II during December 1941, the US Navy had 171 operational destroyers, including 71 of the two related ‘flushdeck’ types that had been built to the extent of 272 destroyers in World War I. Some 31 and 40 of these were of the ‘Wickes’ and ‘Clemson’ classes. After the completion of ships already under construction at the end of World War I, construction of destroyers had been ended in the USA until the early 1930s, when destroyer developments in other parts of the world finally persuaded the Americans to undertake the construction of a more advanced type in the form of the ‘Farragut’ class of seven ships with a displacement of 1,395 tons, an armament of five 5-in (127-mm) guns in single mountings and eight 21-in (533-mm) torpedo tubes in two quadruple mountings, and a speed of 36.5 kt on the 42,800 hp (31910 kW) delivered to two shafts by geared steam turbines. In the period leading up to World War II, the US Navy developed the conceptual design of the ‘Farragut’ class via the ‘Mahan’ class of 18 ships (five 5-in/127-mm guns in single mountings, 12 21-in/533-mm torpedo tubes in three quadruple mountings) to the ‘Craven’ class of 22 ships (four 5-in/127-mm guns in single mountings, four 1.1-in anti-aircraft guns in single mountings and 16 21-in/533-mm torpedo tubes in four quadruple mountings.

A parallel course of evolution produced the eight and five ships of the ‘Porter’ and ‘Somers’ classes respectively for the squadron leader task. The basic design of the ‘Porter’ class included a displacement of 1,850 tons, an armament of eight 5-in (127-mm) guns in four twin mountings and eight 21-in (533-mm) torpedo tubes in two quadruple mountings, and a speed of 37 kt on the 50,000 hp (37280 kW) delivered to two shafts by geared steam turbines, and the ‘Somers’ class differed mainly in its uprated propulsion arrangement with 52,500 hp (39145 kW) for a speed of 37.5 kt.

Further development of the basic fleet destroyer concept in the late 1930s led to the ‘Sims’ class of 12 ships that proved to be top-heavy, so one of their five 5-in (127-mm) guns and one of their three quadruple 21-in (533-mm) torpedo tube mountings were soon removed. The same fate befell the early units of the ‘Benson’ class, which was an improved version of the ‘Sims’ class, and itself later upgraded as the ‘Livermore’ class. Construction of the ‘Benson’ and ‘Livermore’ classes totalled 32 and 64 ships respectively.

Classic destroyer design evolution
Experience with these classes paved the way for the ‘Fletcher’ class destroyer that was the US Navy’s most important ship of its type in the first part of World War II. Built to the extent of 178 ships that were delivered from 1942 with a beamier, flushdecked hull, a displacement of 2,050 tons, an armament of five 5-in (127-mm) guns in single mountings, between six and 10 40-mm and 20-mm anti-aircraft guns and 10 21-in (533-mm) torpedo tubes in two quintuple mountings, and a speed of 37 kt on the 60,000 hp (44,870 kW) delivered to two shafts by geared steam turbines.

The destroyers of the ‘Fletcher’ class were supplemented from 1944 by the destroyers of the ‘Allen M. Sumner’ and ‘Gearing’ classes, which were bigger and more heavily armed vessels specifically created for the demands of long-range operations in the western Pacific, where they were often exposed to intensive Japanese air attack by kamikaze as well as conventional aircraft. The 58 ‘Allen M. Sumner’ class destroyers were completed to a standard that included a displacement of 2,200 tons, an armament of six 5-in (127-mm) dual-purpose guns in three twin turrets, 12 40-mm anti-aircraft guns and 10 21-in (533-mm) torpedo tubes in two quintuple mountings, and a speed of 36.5 kt on the 60,000 hp (44870 kW) delivered to two shafts by geared steam turbines. The 99 ‘Gearing’ class destroyers completed in and immediately after the closing stages of World War II as a development of the ‘Allen M. Sumner’ class design with a lengthened hull had a displacement of 2,425 tons, an armament of six 5-in (127-mm) dual-purpose guns in three twin turrets, 12 or 16 40-mm anti-aircraft guns and 10 (none in ships with 16 40-mm guns) 21-in (533-mm) torpedo tubes in two quintuple mountings, and a speed of 35 kt on the 60,000 hp (44870 kW) delivered to two shafts by geared steam turbines.

The US Navy had not initially seen the need for specialised destroyer escorts, and the type was originally ordered in 1941 by the UK, which contracted with American yards for an initial 50 destroyer escorts, or escort destroyers as they were called by the British, before increasing this total to 250 in the following year. By this latter date the USA had entered the war, and soon appreciated the vital nature of the destroyer escort for the protection of troop and equipment convoys in the Pacific, where their faster and more heavily armed destroyer half-brothers were better employed for the protection of carrier and amphibious task forces. Thus only 55 of these American ships were finally transferred to the British, and of the orders placed by 1943 for 1,005 destroyer escorts, 508 were completed as 452 as destroyer escorts (29 of them for transfer to Allies other than the UK) and the other 56 as high-speed transports.

Two types of hull
The ships were completed with two types of hull. The original group of 61 ships was the ‘Evarts’ class with an overall length of 283 ft 4 in (86.36 m), while the others had an overall length of 306 ft 0 in (93.27 m) and were the ‘Buckley’, ‘Rudderow’, ‘Cannon’, ‘Edsall’ and ‘John C. Butler’ classes. The ships of the ‘Evarts’ class had a displacement of 1,140 tons, an armament of three 3-in (76-mm) guns in single mountings, four 40-mm anti-aircraft guns and five 20-mm cannon, and a speed of 21 kt on the 6,000 hp (4475 kW) delivered to two shafts by a Diesel-electric propulsion arrangement.

The ships of the ‘Buckley’ class had a displacement of 1,400 tons, an armament of three 3-in (76-mm) guns in single mountings, six 40-mm anti-aircraft guns and three 21-in (533-mm) torpedo tubes, and a speed of 23.5 kt on the 12,000 hp (8950 kW) delivered to two shafts by a turbo-electric propulsion arrangement. The following ‘Rudderow’ class had a displacement of 1,450 tons, an armament of two 5-in (127-mm) guns in single mountings, 10 40-mm anti-aircraft guns and three 21-in (533-mm) torpedo tubes, and a speed of 24 kt on the 12,000 hp (8950 kW) delivered to two shafts by a turbo-electric propulsion arrangement. However, in the ‘Cannon’ class a Diesel-electric propulsion arrangement had to be adopted, as in the ‘Buckley’ class, because of shortages of turbo-electric equipment, and this resulted in a displacement of 1,240 tons, an armament of three 3-in (76-mm) guns in single mountings, six 40-mm anti-aircraft guns and three 21-in (533-mm) torpedo tubes, and a speed of 21 kt on the 6,000 hp (4475 kW) delivered to two shafts by the Diesel-electric propulsion arrangement. The ‘Edsall’ class was similar, and its details therefore included a displacement of 1,200 tons, an armament of three 3-in (76-mm) guns in single mountings, eight 40-mm anti-aircraft guns and three 21-in (533-mm) torpedo tubes, and a speed of 21 kt on the 6,000 hp (4475 kW) delivered to two shafts by a Diesel-electric propulsion arrangement. The ships of the final ‘John C. Butler’ class were somewhat different, and they were completed to a standard that included a displacement of 1,350 tons, an armament of two 5-in (127-mm) guns in single mountings, 10 40-mm anti-aircraft guns and three 21-in (533-mm) torpedo tubes, and a speed of 24 kt on the 12,000 hp (8950 kW) delivered to two shafts by geared steam turbines.

French destroyer Le Fantasque (Croiseur léger) in 1943French destroyers
Of the other Allied powers in World War II, only France operated a large navy to any effect, and then in any strategically meaningful manner till the time of the French capitulation June 1940. The French destroyer force, in order of design, included the six large destroyers of the ‘Jaguar’ class launched in 1923 and 1924 before being completed to a standard that included a full-load displacement of 3,050 tons and a primary armament of five 5.1-in (130-mm) guns in single mountings, the 24 medium destroyers of the ‘Simoun’ class launched in two groups between 1924 and 1929 before being completed to a standard that included a full-load displacement of 2,000 tons and a main armament of four 5.1-in (130-mm) guns in single mountings, the 18 large destroyers of the ‘Guépard’ class launched in four groups between 1928 and 1932 before being completed to a standard that included a full-load displacement of 3,400 tons and a primary armament of five 5.5-in (139-mm) guns in single mountings, the six large destroyers of the ‘Le Fantasque’ class launched in 1933 and 1934 before completion to a standard that included a full-load displacement of 3,400 tons and a primary armament of five 5.5-in (139-mm) guns in single mountings, the 12 small destroyers of the ‘La Melpomène’ class launched between 1935 and 1937 before being completed to a standard that included a full-load displacement of 900 tons and a primary armament of two 3.9-in (100-mm) guns in single mountings, the two ships of the ‘Mogador’ class that were the last word in large destroyer design and capability after launch in 1936 and 1937 before being completed to a standard that included a full-load displacement of 4,020 tons, a primary armament of eight 5.5-in (139-mm) guns in four twin mountings, and a speed of 39 kt on the 92,000 hp (75265 kW) delivered to two shafts by geared steam turbines, and the eight large destroyers of the ‘Le Hardi’ class launched between 1938 and 1939 before being completed to a standard that included a full-load displacement of 2,575 tons and a primary armament of six 5.1-in (130-mm) guns in three twin mountings.

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