L and M-class destroyer


The L and M class was a class of sixteen destroyers which served in the British Royal Navy during World War II. The ships of the class were launched between 1939 and 1942.
The L class were approved under the 1937 Naval Estimates. Four of these ships were built with armament instead of 4.7 inch. Six of the eight were war losses, with the surviving pair being broken up in 1948.
The M Class were built under the 1939 Naval Estimates. They served in the Home Fleet until 1944 and then went to the Mediterranean. Three were wartime losses; of the five survivors, the Musketeer was broken up in 1955 and the other four sold to Turkey in 1958.

Design details

The armament of the class was subject of considerable debate, as the proponents of heavier anti-aircraft armaments for such vessels were at last beginning to be listened to by the Admiralty. This came mainly as a result of the lessons learned during the Spanish Civil War – i.e., military aircraft were now sufficiently advanced to pose a major threat to land and sea targets.
The ships of the L and M class had single funnels, like the previous J class, a tripod foremast and a short mainmast just aft of amidships. One feature of note was the bridge design. From the to the, all Royal Navy destroyers shared a distinctive wedge-shaped face to the bridge, incorporating a bulletproof wheelhouse, raised in order that the helmsman could see over the guns. The increased height of the new gunhouses of the L class meant that the wheelhouse was raised further, and the sloped roof of the wheelhouse was almost flat. This feature was unique to the L and Ms.
As ordered, the class comprised a leader and 7 destroyers. Each ship was to mount six guns and 8 torpedo tubes. Close range armament had still to be decided, with the expected time of delivery being a crucial factor.
They were the first British destroyers to have their guns in fully enclosed mountings. They also continued the practice of making the leader almost indistinguishable from the rest of the class, having only more extensive cabin accommodation and better radio equipment

Main armament

As ordered, the ships were to have six QF Mark XI guns in Mark XX twin mountings in 'A', 'B', and 'X' positions. The 'X' mount gave an estimated arc of fire of 320 degrees at low elevations and 360 degrees at elevations above around 20 degrees. The Mark XI gun itself was a major improvement on the previous version in that it threw a shell. The Mark XX mount was fully enclosed and supposedly weatherproof; in service, crews found otherwise. It also allowed the guns to be elevated independently. The Mark XX was not technically a turret, as the ammunition feed system was distinct from the weapon mounting, and did not train with the revolving mass. This meant that ammunition supply when the guns were at the limit of training was somewhat difficult. This also meant that the ammunition hoists had to be located between the guns just as in the USN 5" guns. As a result, the axes of the guns were very widely spaced, a feature instantly obvious with the Mark XX mounting.
The Mark XX mounting permitted an increased elevation to 50 degrees. However, this still limited the engagement time against enemy aircraft, although medium calibre guns posed little threat to dive bombers prior to the use of radar proximity fuzed ammunition. The Imperial Japanese Navy had already introduced a 5-inch gun with 70-degree elevation into service which had very poor performance as an anti-aircraft weapon, while the United States Navy's 5"/38 cal Mark 32 mount could elevate to 85 degrees. The 4.5-inch guns fitted to Ark Royal were already in service and capable of elevations of 80 degrees, although the mountings were not suitable for a destroyer-size ship. Coupled with the lack of powered elevation, the Mark XX mounting was compromised in its chosen anti-aircraft role, although it compared favourably with any similar weapon in the Axis inventory.
Another development regarding the main armament was the adoption of a combined high-angle/low-angle director tower, the HA/LA Mk.IV. This was never entirely satisfactory in the HA mode, and was at least a ton overweight. It was later reworked, somewhat unsuccessfully again, as the Mk.I "K tower" of the Z class. These ships used the Fuze Keeping Clock HA Fire Control Computer. Despite its problems, the L and M class' director tower and its Type 285 radar provided better high-angle fire control than any similar Axis destroyer, the vast majority of which did not have any high-angle fire control system, much less a dedicated AA fire control radar.
As originally ordered, the class had no close-range armament at all, as the various departments could not agree on what to fit. Arguments raged as to the effectiveness of mounting one or two four-barrelled 2 pdr "pom poms", one pom-pom and one of the multiple machine guns then in development, one pom-pom and the traditional 0.5-inch Vickers machine gun. The argument was stoked by the manufacturing schedules, the poor performance of the development models of the 0.661 and a number of younger officers dissatisfied with available anti-aircraft weaponry. Eventually, development of the 0.661 was dropped as it clearly would not be available and effective in a sensible timescale, this simplified the arguments somewhat.
The outbreak of war focused minds. Apart from the AA armament issue concerns started to be raised about progress generally. By February 1940 the two factors led to a proposal to change the design of four of the 'L's and fit a main armament of 4-inch Mark XVI* guns in Mark XIX High Angle/Low Angle twin mounts as used as secondary armament in the Southampton-class cruisers already in service and main armament in the Black Swan class of sloops then under construction. Associated changes were provision of two quadruple 0.5-inch machine guns. All ships of this class except Lightning and Laforey carried a four-barrel 2 pdr pom-pom.
The lessons of the Norwegian campaign and at Dunkirk drove home the need for this change and it was agreed in July 1940 that there were also to be four of the twin mounts instead of the originally proposed three. The fourth was to be at the forward end of the after superstructure which cut down on the fire arcs of both mounts but ensured the fourth would still be available for use in heavy weather.
Not all senior officers were in favour and some openly expressed opinions that it would mean the ships could not successfully fight their foreign equivalents. Experience in the Mediterranean, especially that of Force K which contained two of the 4-inch 'L's, showed that the loss of gun power against surface targets was balanced against a higher rate of fire.
Review of AA armament continued and in October a decision was taken to remove the after bank of torpedo tubes and fit a single 4-inch HA gun instead and that is how the gunned ships eventually went to sea, although some surviving ships, including Matchless and Marne, had the after tubes replaced later in the war.

Proposed conversion

In the early 1950s, it was proposed to convert the five remaining ships of the M class, together with seven War Emergency Programme destroyers to Type 62 Air Direction Frigates. The conversion would have involved replacement of the ships' armament and sensors. The initial proposal would have armed the ships with a twin 4-inch gun mount, a twin 40 mm Bofors gun and a Squid anti-submarine mortar. Type 982 and 983 air direction radars would be fitted, as would Type 162 and 166 sonars. In March 1952, the programme was reduced, as the War Emergency Destroyers were too small to accommodate the heavy radars. Later that year, it was decided to substitute a US twin 3"/50 caliber gun mount for the 4-inch guns. The project was finally abandoned in May 1954, partly owing to the condition of the ships and poor shock-resistance.

Ships

L class

The L class were approved under the 1937 Naval Estimates. Four of these ships were built with armament. Six of the eight were war losses, with the surviving pair being broken up in 1948.
ShipPennant numberBuilderLaid downLaunchedCommissionedFate
, flotilla leaderG99Yarrow & Company, Scotstoun1 March 193915 February 194126 August 1941Lost on 30 March 1944.
G87Yarrow & Company, Scotstoun1 March 193928 November 194013 May 1941Lost on 9 April 1942.
, ex-LarneG63Cammell Laird & Company, Birkenhead18 October 193828 July 194018 February 1941Lost on 17 January 1942.
G40Cammell Laird & Company, Birkenhead20 December 193828 January 194120 July 1941Lost on 11 May 1942.
G74Hawthorn Leslie & Company, Hebburn1 November 193826 December 193919 December 1940Lost on 26 March 1942.
G55Hawthorn Leslie & Company, Hebburn15 November 193822 April 194028 May 1941Lost on 12 March 1943.
G32Scotts Shipbuilding & Engineering Company, Greenock23 November 19384 November 194030 January 1942Broken up 1948.
G15Scotts Shipbuilding & Engineering Company, Greenock23 November 19388 October 194131 October 1942Broken up 1948.

M class

The M Class were built under the 1939 Naval Estimates. They served in the Home Fleet until 1944 and then went to the Mediterranean. Three were wartime losses; of the five survivors, the Musketeer was broken up in 1955 and the other four sold to Turkey in 1958.
ShipPennant numberBuilderLaid downLaunchedCommissionedFate
G14Scotts Shipbuilding & Engineering Company, Greenock24 January 194030 December 19416 August 1942Transferred to Turkey 1959 as Alp Arslan.
, ex-MarksmanG23Scotts Shipbuilding & Engineering Company, Greenock7 July 193928 July 19428 April 1943Sunk by T5 fired by U-990 and sank quickly in position 71.17N 13.30E in Barents Sea on 25 February 1944. Only 17 out of a total of over 217 in the ship's company were rescued by HMS Impulsive.
G86Fairfield Shipbuilding & Engineering Company, Govan7 December 19392 December 19415 December 1942Broken up at Sunderland 6 December 1955.
G90Fairfield Shipbuilding & Engineering Company, Govan7 December 19392 March 19425 December 1942Loaned to the Polish Navy and renamed ORP Orkan. Sunk by torpedo from U-boat in the North Atlantic on 8 October 1943.
G52Alexander Stephen & Sons, Linthouse14 September 19404 September 194126 February 1942Transferred to Turkey 1959 as Kilicali Pasha.
G74Alexander Stephen & Sons, Linthouse14 September 19403 November 194112 August 1942Transferred to Turkey 1959 as Piyale Pasha.
G35Vickers-Armstrongs, Walker23 October 193930 October 19402 December 1941Transferred to Turkey 1959 as Maresal Fevzi Cakmak.
G44Vickers-Armstrongs, Walker23 October 193912 December 19404 August 1942Sunk by torpedo from U-boat in the Western Mediterranean on 10 November 1942.

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