At the start of World War II, the Royal Navy operated a range of destroyer classes. Some of these were legacies of World War I, some were designed during the inter-war years and the rest were the result of wartime experience and conditions. British-built and -designed vessels were also supplied to and built by allied navies, primarily the Australian and Canadian navies.

Evolution

British destroyer flotillas were formed from single classes, with a slightly adapted flotilla leader; the aim had been to produce a flotilla each year. As a broad summary, British destroyers developed from the successful s of World War I, increasing in complexity until World War II. The Royal Navy then needed new ships quickly to increase numbers, replace losses and exploit experience and so design became simplified and cheaper to produce, with greater anti-aircraft and anti-submarine power (War Emergency Programme).

British destroyer design had developed with incremental changes in the inter-war years, apart from the larger which was not repeated. In 1937, there was a radical change in destroyer design with the production of the more complex J, K and N classes and the modified Ls and Ms. It was deemed to be a successful design, but was discontinued in favour of the a simpler War Emergency Programme design.

Later in the war, the was developed, with a greatly enhanced anti-aircraft capability.

Convoy escorts British practice had been to produce fleet destroyers and to relegate older vessels to escort duties. This was unsatisfactory for several reasons. Firstly, the fleet destroyers' power plants were designed for the higher speeds required of the naval fleet: they were inefficient when used for convoy speeds. Secondly, fleet destroyer range was inadequate and this was exacerbated at convoy speeds; significant adaptations were necessary. Thirdly, armament did not address the air and submarine threats to convoys and essential inclusions affected stability. Lastly, there were insufficient units and the urgent need was more for numbers rather than quality of build.

This need was initially met by adapting elderly destroyers from the Royal Navy and the United States Navy. The s, which were ordered from early 1939, were the first response by the Admiralty to the circumstances of convoy escort, but they were really suitable for just North Sea and Mediterranean Sea service. Later, new types of vessel were built for escort work in the North Atlantic - and s, , and s and s.

Weapon systems The armament, naturally, reflected the changing circumstances of warfare and technological progress. At first, the destroyers were expected to escort, augment and protect the battleline, that is, the capital ships. This was reflected in the emphasis on the installation and development of anti-ship weaponry - guns and torpedoes. As a result, the "legacy" and inter-war classes were deficient in anti-submarine (ASW) and anti-aircraft (AA) weapon systems. The effect can be seen in the particularly high rate of loss to air attack in the early war years.

Attempts to resolve this resulted in both improved new ship designs and in modifications to existing ships. AA weapons were improved in number, power and fire control, with some classes equipped with main armament capable of AA use, even at the expense of reduced calibre. Secondary armament progressed from largely ineffective batteries of machine-guns and 2 pdr "pom-pom"s to Bofors and Oerlikon rapid-fire cannon, sometimes at the expense of torpedo tubes. Some classes were fitted with a single AA gun, but this was unsatisfactory and discontinued. Effectiveness was further improved by improvements in fire control, such as the adoption of the Dutch Hazemeyer system.

At the outbreak of war, ASW weapons were limited to the depth charge and ASDIC (sonar). The weaknesses of this combination had been known before the start of the war, but the development of a replacement - the ahead-throwing weapon - had not been advanced with much urgency. The Hedgehog spigot mortar arrived in early 1943 and was fitted in older destroyers converted for convoy escort work. Hedgehog was followed by the Squid mortar later in the same year. Although it was trialled on , it was rushed into service in Castle-class corvettes and Loch-class frigates and few destroyers received this weapon before the cessation of hostilities.

The effectiveness against surface threats was improved by new guns and the introduction of radar. Radar, in particular, gave British destroyers a decisive advantage such as in night actions against the Italian Regia Marina, enabling clear victories at Cape Bon and off Sfax. Gun mountings were developed to provide high angle, anti-aircraft capability and all round gun houses.

Guns

QF 4.7 inch - standard main battery weapon until supplanted by the QF 4.5 inch in mid-war. HA version not developed, so limited in its anti-aircraft use. QF 4.5 inch - an HA version was used to enable anti-aircraft use. Despite a smaller calibre, it used a heavier shell than the QF 4.7 inch. QF 4 inch Mk V - World War I dual-purpose gun and coastal defence gun QF 4 inch Mk XVI - dual-purpose gun, superseded the earlier QF 4 inch Mk V QF 12 pounder QF 6 pounder QF 2 pounder ("pom-pom") QF 40 mm (Bofors) QF 20 mm (Oerlikon) QF 0.5 inch (Vickers) - mounted as an anti-aircraft weapon but, in practice, ineffective. QF 0.303 (Lewis)

Torpedoes 21 inch Mark IX 21 inch Mark X 21 inch Mark XI

Anti-submarine Depth charges Hedgehog spigot mortar Squid mortar

Actions

It is impractical to give detail here of the entirety of British destroyer actions during the war. British destroyers were engaged in the Arctic, Atlantic, Pacific and Indian Oceans; the North and Mediterranean seas. Of the 389 Australian, British and Canadian destroyers involved in the war, over 150 were lost or damaged beyond repair. They were used to defend and escort convoys and the fleet, to perform aggressive operations against enemy merchant and naval ships, to act as transports and to deliver bombardments in support of armies. Here, however, is a sample of significant and famous actions:

Battle of Cape Bon, 1941

The British 4th Destroyer Flotilla — four destroyers (, , and the Dutch destroyer ) - intercepted and sank the Italian light cruisers and . The action took place off Cape Bon, Tunisia.

Capture of U-110, 1941

While escorting convoy OB318, captured U-110 and, critically, its top-secret Enigma cipher machine and documentation.

St. Nazaire Raid, 1942

The Town-class destroyer , the former USS Buchanan, was adapted to resemble a German destroyer and, loaded with troops and tons of explosive, rammed and destroyed a strategically important dry dock in St Nazaire.

Battle of North Cape, 1943

The sinking of by an Allied force that included HMS Savage, Saumarez, Scorpion, HNoMS Stord, HMS Opportune, Virago, Musketeer and Matchless.

Sinking of Haguro, 1945

The was intercepted by the 26th Destroyer Flotilla (HMS Saumarez, Verulam, Venus and Virago) and sunk 55 miles (89 km) off Penang, on 16 May 1945.

Legacy classes

V and W

The s had been ordered from 1916 onwards in response to increasing German specifications and to provide vessels capable of operating in poor weather with the fleet. By year's end, 25 Vs and 25 Ws had been ordered. Compared with the earlier M and classes, the Vs and Ws were larger with better freeboard and increased armament, initially four or five gun mountings and four or six torpedo tubes.

It was learnt that the Germans would mount guns, so the gun mount was adopted for sixteen further ships that were ordered in 1918, the "modified V & Ws".

Although still in service in the 1930s, these were no longer frontline units, but necessity saw thirty-nine adapted for escort duties in World War II.

Town

The fifty s were elderly American destroyers transferred to the Royal Navy and the Canadian and Norwegian navies in an Anglo-American Destroyers-for-bases deal that preceded Lend-Lease. They comprised three s, twenty s and twenty-seven , dating from World War I.

Like the Vs and Ws, adaptations were required for escort work. They were unpopular with officers, who found them relatively unmanoeuvrable, and with crews, whose accommodation was both cramped and damp. Nonetheless, they filled a need at a critical time.

Inter-war classes From 1930, the Royal Navy commissioned one destroyer flotilla each year, at first with eight ships plus a slightly larger flotilla leader. Additional ships were built as required for sale abroad. The convention was to assign a letter to each class, ships' names starting with that letter, except for the leader.

and were launched in 1926 and they were the prototypes for the following nine classes (A to I) launched between 1929 and 1941. The classes J to N, 40 ships launched between 1938 and 1940, were more complex, with heavier armament and expensive to build. The pattern was cut short by the need for numbers of basic ships arising from the hard lessons of war.

The s broke with the incremental evolution of the inter-war classes. They were larger ships designed to match the heavier destroyers built by several other navies.

A and B

The A class was the first full class of the inter-war years and reckoned to be a successful design for their time. A full flotilla of nine was built for the Royal Navy, between 1928 and 1931, plus two more for the Royal Canadian Navy (RCN). Eight were lost during the war.

They displaced 1,350 tons and they could attain . Main armament was four 4.7-inch QF Mark IX guns, in single mounts, and eight torpedo tubes. Anti-aircraft weaponry consisted of one of the unsatisfactory Mark II 20 cwt QF gun and two 2-pounder Mark II pom pom guns. Thirty depth charges were carried.

A near copy of the As, the B class nine ship flotilla was built between 1929 and 1931. Five were lost.

They were only slightly larger than the A class, 1,360 tons (standard). The original kit of four 4.7-inch and eight 21-inch torpedo tubes was reduced before the start of the war to three and four respectively, to boost anti-submarine (ASW) capability. Anti-aircraft weaponry varied in the class, four Oerlikon 20 mm cannon being installed on some ships.

C and D

Two nine ship flotillas were planned. Only five C-class ships were built and all were transferred to the RCN. Two were lost during the war, one accidentally rammed by the cruiser . A third was also accidentally destroyed after the war.

All nine D-class ships were commissioned into the Royal Navy. One was later transferred to the RCN. These had a greater ASW capability designed in, at the expense of minesweeping. Only two, including the Canadian ship survived the war.

Ships of both flotillas retained all of their four 4.7s, as well as the 3-inch and 'pom pom' anti-aircraft guns. In addition, eight 12.7 mm machine guns were fitted.

E and F Two nine-ship flotillas were built. The Es were built between 1931 and 1934 and the Fs one year later. One E-class ship was transferred to the RCN and another to the Royal Hellenic Navy (Greece). Three, including the Greek and Canadian ships, survived the war. Two F-class ships were transferred to the RCN; five survived the war, one survivor was sold to the Dominican Republic.

These two flotillas were substantially a continuation of the design, maintaining the full 4.7-inch gun and torpedo weaponry, but with variations for secondary armament. The engine room compartmentation was an improvement over the C and D classes.

G and H

Another pair of flotillas, the s continued the gentle evolution of the design with a revised engine room layout. Only two of nine G-class ships survived the early war years and they were transferred to the RCN and the Polish Navy during the war.