"M" Class Destroyer (1914)

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A total of 103 destroyers of the "M" Class were completed, 13 in the 1913-1914 programme and 90 further ships as part of the successive orders of the War Emergency Programme.

They were essentially improved "L" class destroyers with 6 knots more speed, but there was a mix of Admiralty design vessels (79) and a diverse set of builder's specials (22 ships).[1]

The War Emergency Programme ships are often called the Repeat "M" Class, but the distinction between them and the original 13 vessels is largely fiduciary and less important than the design differences attributable to specials and Admiralty design as well as the manic diversity the Royal Navy's ships exhibited even when it intended a uniform class. For this convoluted reason, "Repeat 'M' Class" will be used in a passing manner here, and all 103 ships generally called "M" class destroyers.

Electric Logs

Based on prior recent orders, it seems likely that these ships were completed with two Trident Electric Logs and one Charthouse Receiver.[2]



In 1916, it was stated that "new destroyers" have two 26.25 kw dynamos arranged in parallel.[3] It is possible that this applied to some or all of this class.


Admiralty M

The ships' capacity for 285 tons of fuel, delivered the following endurance.[4]

Knots Tons / hour Endurance
radius (nm)
14 2.0 135 1,890
16 2.5 108 1,728
18 3.2 84 1,512
20 4.0 67 1,340
22 5.0 54 1,1188
24 6.2 43 1,032
26 8.2 33 858
28 10.8 25 700
30 12.5 21 630

Yarrow M

The ships' capacity for 255 tons of fuel, delivered the following endurance.[5]

Knots Tons / hour Endurance
radius (nm)
14 1.8 133 1,862
16 2.2 109 1,744
18 2.8 85 1,530
20 3.4 70 1,400
22 4.5 53 1,166
24 5.5 43 1,032
26 7.0 34 884
28 8.5 28 784
30 10.5 22 660

Thornycroft M

The ships' capacity for 275 tons of fuel, delivered the following endurance.[6]

Knots Tons / hour Endurance
radius (nm)
14 1.6 162 2,268
16 2.0 130 2,080
18 2.4 108 1,944
20 3.2 81 1,620
22 4.2 62 1,364
24 5.6 46 1,104
26 7.0 37 962
28 9.0 29 812
30 11.5 22 660


4-in Guns

Their three 4-in Q.F. Mark IV guns on P. IX mountings on the centre line were just as in the preceding "L" class destroyers and the final seven of the Acasta class.[7] There were 120 rounds per gun: 36 common, 84 lyddite, an an additional 19 practice rounds. [8]

The mounting could elevate 20 degrees and depress 10 degrees, but its sight could only elevate 15 degrees and the range dial was actually only graduated to 12.5 degrees (7,900 yards). "This was soon remedied by the supply of additional sight strips graduated to the extreme range of 10,200 yards."[9]

These gear-worked sights had gearing constants of 26.66 and range dials for 2200 fps, and 1-in aiming rifle. MV could be corrected by a cam pointer allowing for a decrease to 2000 fps.

Unlike some P. IX sights, these were not F.T.P. sights.

The midship gun was supplied with ammunition from the forward stores.[10]

The deflection gearing constant was 52.6 with 1 knot equal to 3.18 arc minutes, corresponding to 2200 fps at 2000 yards. Drift was corrected by inclining the sight about pivot pins 2 degrees.

The layer's telescope sight line was 12.5 inches above the bore, and 21.45 inches left. The trainer's telescope sight line was 12.5 inches above and 17.4 inches right. Open sights were 13.3 inches above the bore and 24.35 inches left for layer and 20.3 inches right for trainer.

The sight had a temperature correcting scale plate and a "C" corrector.

The layer had an open sight. The trainer's sight could be used as a free sight with a counterweight.

During the war, some of the ships were required to land their aft gun to accommodate depth charges.[11]

In late September, 1914, the Admiralty ordered that the guns on the Tribals and later classes were to be given loading lights, initially on temporary circuits. By inference, most or all of these ships were probably completed with this equipment in place.[12]

Other Guns

They may have carried one (later two) 1-pdr H.A. guns (later 2-pdr) as well as 4 mines on the upper deck.[13] The first six ships were to complete with H.A. pompoms, and the others to receive theirs as they became available.[14]

By 1920, some or all had one 2-pdr pompom for air defence.[15]


21-in D.R. [Double Revolving] Torpedo Mounting Mark II[16]
The "M" Class's Mark III was similar, but lacked the guard rails around the training platform, as it was fitted on the centreline.

In 1917, at least some of these ships were using 21-in Mark II**** torpedoes and 21-in Mark II***** torpedoes.[18]

Other Weapons

Depth charges were added to most destroyers, necessitating that some land their aft gun to accommodate the outfit.[19]

Fire Control

Range and Order Instruments[20]

By the end of 1915, at least, these ships had or were to be provided a range and order data system similar recent Barr and Stroud patterns.[21]

The scheme placed the combined transmitter on the forebridge, and a combined receiver near the sightsetter position of each gun. Ranges from 0 to 9900 yards in increments of 100 yards, and orders were "Independent", "Control" and "Fire" with illuminated indicators and a red indicator on the receivers to signal loss of power from the battery pack located below decks.

Mid 1916 Outfit

Experiments from February with two Grand Fleet destroyers employing dumaresqs and Vickers Range Clocks and voicepipes showed definite advantages over ships using unaided spotting and voicepipes, even when the crews had no special training in the new equipment. Tests were also conducted to find a rangefinder suitable to the lively and cramped platform that destroyers provided. This led to an order on 3 April, 1916 that each T.B.D. of "M" class and later should be equipped with:[22][23]

Two ratings, trained before coming aboard, were added to the crew to work the equipment. The clocks and rangefinders were issued in the following three months, and the dumaresqs a few months later. The data instruments did not become available in numbers until 1917. By mid-1917, the whole system was broadly in place in the destroyers of the Grand Fleet and in the Harwich Force.[24]


The first installations of the British Destroyer Director Firing System in this class were being effected in May 1918.[25]

Torpedo Control

Fire Gong and Lamp Reply Circuits[26]
found in 20 ships using mechanical or pressure gear for orders and deflection

The ships had a single sighting position located high up in the centre of the bridge, which required them to thus have only a single set of firing pushes or keys as well as keys for operating buzzers at the tubes.[27]

Twenty of the ships used pressure and/or mechanical equipment to relay orders and deflections from the control position to the tubes, augmented by fire gong and lamp reply circuits: Manly, Mentor, Mastiff, Matchless, Melpomene, Nereus, Partridge, Milne, Minos, Miranda, Moorsom, Murray, Myngs, Nepean and Radstock used Wise Type C gear for orders and deflection, and Mentor, Meteor, Pasley, Patriot and Morris used Chadburn's Torpedo Order Telegraph with Wise Pressure Telegraphy System Type B supplying deflection.[28]

Electrical Instruments[29]
found in most "M" class destroyers

The majority of the ships, however, used completely electrical systems. These ships employed a single Mark I deflection transmitter at the control position, and separate order transmitters and keys, one for the forward tubes and one for the aft. The forward tubes had a buzzer, and the aft ones had a rattler.[30]


By November 1918, Prince and Meteor were fitted to carry 38 mines. The torpedo tubes and guns removed when the mines were shipped could be placed back aboard with enough notice.[31]

See Also


  1. Conway's. pp. 76-77, 79-80.
  2. Admiralty Weekly Order No. 967 of 27 Mar, 1914.
  3. Annual Report of the Torpedo School, 1916. p. 120.
  4. Battlecruiser Force Signal Orders (1 August, 1918), ADM 137/2135
  5. Battlecruiser Force Signal Orders (1 August, 1918), ADM 137/2135
  6. Battlecruiser Force Signal Orders (1 August, 1918), ADM 137/2135
  7. The Sight Manual, 1916. p. 80, 108, Plates 33, 34.
  8. March. British Destroyers. p. 143.
  9. The Technical History and Index, Vol. 4, Part 34. p. 13.
  10. March. British Destroyers. Plate 17/A.
  11. The Technical History and Index, Vol. 4, Part 34. p. 14.
  12. Admiralty Weekly Order No. 416 of 29 Sep, 1914.
  13. March. British Destroyers. p. 143, 145.
  14. March. British Destroyers. p. 146.
  15. Technical History and Index, Vol 4, Part 34, p. 16.
  16. Annual Report of the Torpedo School, 1913. Plate15.
  17. March. British Destroyers. Plate 18/B.
  18. Annual Report of the Torpedo School, 1917. p. 61.
  19. The Technical History and Index, Vol. 4, Part 34. p. 14.
  20. Admiralty.  Handbook of Fire Control in Torpedo Boat Destroyers of "M" Class and Later and Flotilla Leaders, 1915, Plate XVI.
  21. Admiralty. Handbook of Fire Control in Torpedo Boat Destroyers of "M" Class and Later, and Flotilla Leaders, 1915, p. 3.
  22. The Technical History and Index, Vol. 3, Part 23. p. 31.
  23. Progress in Naval Gunnery, 1914-1918. p. 35.
  24. The Technical History and Index, Vol. 3, Part 23. pp. 31, 32.
  25. The Technical History and Index, Vol. 3, Part 23. p. 12.
  26. Annual Report of the Torpedo School, 1917. Plate 85.
  27. Annual Report of the Torpedo School, 1917. p. 211.
  28. Annual Report of the Torpedo School, 1917. p. 211.
  29. Annual Report of the Torpedo School, 1917. Plate 84.
  30. Annual Report of the Torpedo School, 1917. p. 211, Plate 84. (C.I.O. 439/17.).
  31. Admiralty. Annual Report of the Torpedo School Mining Appendix, 1917-1918, p. 11. Plate 7.


"M" Class Destroyer
Admiralty Design (Three Funnels)
Matchless Murray Myngs Milne Moorsom
Morris Mons Marne Mystic Maenad
Manners Mandate Magic Moresby Marmion
Martial Mary Rose Menace Mameluke Marvel
Mischief Mindful Nonsuch Negro Nessus
Noble Nizam Nomad Nonpareil Norman
Northesk North Star Nugent Obedient Obdurate
Onslaught Onslow Opal Ophelia Opportune
Oracle Orestes Orford Orpheus Octavia
Ossory Nestor Napier Narborough Narwhal
Nicator Norseman Oberon Observer Offa
Orcadia Oriana Oriole Osiris Paladin
Parthian Partridge Pasley Plucky Portia
Pheasant Phoebe Pigeon Plover Penn
Peregrine Pelican Pellew Petard Peyton
  Prince Pylades Medina Medway  
Thornycroft Specials (Three Funnels)
Mastiff Meteor Michael Milbrook Minion
Munster Nepean Nereus Patrician Patriot
  Rapid Ready  
Yarrow Specials (Two Funnels)
Miranda Minos Manly Moon Morning Star
Mounsey Musketeer Nerissa Relentless Rival
Hawthorn Leslie Specials (Four Funnels)
  Mansfield Mentor  
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