"M" Class Destroyer (1914)

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).

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.

Overview of 103 vessels
Citations for this data available on individual ship pages
Name	Builder	Laid Down	Launched	Completed	Fate
Matchless	Swan Hunter		5 Oct, 1914		Oct, 1921
Murray	Palmer Shipbuilding and Iron Company		6 Aug, 1914		May, 1921
Myngs	Palmer Shipbuilding and Iron Company		24 Sep, 1914		May, 1921
Milne	John Brown & Company		5 Oct, 1914		Sep, 1921
Moorsom	John Brown & Company		20 Dec, 1914		Nov, 1921
Morris	John Brown & Company		19 Nov, 1914
Mons	John Brown & Company		1 May, 1915
Marne	John Brown & Company		29 May, 1915
Mystic	William Denny & Brothers		26 Jun, 1915
Maenad	William Denny & Brothers		10 Aug, 1915
Manners	Fairfield Shipbuilding and Engineering Company		15 Jun, 1915
Mandate	Fairfield Shipbuilding and Engineering Company		27 Apr, 1915
Magic	J. Samuel White		10 Sep, 1915
Moresby	J. Samuel White		20 Nov, 1915
Marmion	Swan Hunter		28 May, 1915		Collision 21 Oct, 1917
Martial	Swan Hunter		1 Jul, 1915
Mary Rose	Swan Hunter		8 Oct, 1915		Sunk 17 Oct, 1917
Menace	Swan Hunter		9 Nov, 1915
Mameluke	John Brown & Company		14 Aug, 1915
Marvel	William Denny & Brothers		7 Oct, 1915
Mischief	Fairfield Shipbuilding and Engineering Company		12 Oct, 1915
Mindful	Fairfield Shipbuilding and Engineering Company		24 Aug, 1915
Nonsuch	Palmer Shipbuilding and Iron Company		8 Dec, 1915
Negro	Palmer Shipbuilding and Iron Company		8 Mar, 1916		Collision 21 Dec, 1916
Nessus	Swan Hunter		24 Aug, 1915		Collision 8 Sep, 1918
Noble	Alexander Stephen & Sons		25 Nov, 1915
Nizam	Alexander Stephen & Sons		6 Apr, 1916
Nomad	Alexander Stephen & Sons		7 Feb, 1916		Sunk 31 May, 1916
Nonpareil	Alexander Stephen & Sons		16 May, 1916
Norman	Palmer Shipbuilding and Iron Company		20 Mar, 1916
Northesk	Palmer Shipbuilding and Iron Company		5 Jul, 1916
North Star	Palmer Shipbuilding and Iron Company		9 Nov, 1916
Nugent	Palmer Shipbuilding and Iron Company		23 Jan, 1917
Obedient	Scotts Shipbuilding and Engineering Company		6 Nov, 1915
Obdurate	Scotts Shipbuilding and Engineering Company		21 Jan, 1916
Onslaught	Fairfield Shipbuilding and Engineering Company		4 Dec, 1915
Onslow	Fairfield Shipbuilding and Engineering Company		15 Feb, 1916
Opal	William Doxford & Sons		11 Sep, 1915
Ophelia	William Doxford & Sons		13 Oct, 1915
Opportune	William Doxford & Sons		20 Nov, 1915
Oracle	William Doxford & Sons		23 Dec, 1915
Orestes	William Doxford & Sons		21 Mar, 1916
Orford	William Doxford & Sons		19 Apr, 1916
Orpheus	William Doxford & Sons		17 Jun, 1916
Octavia	William Doxford & Sons		21 Jun, 1916
Ossory	John Brown & Company		9 Oct, 1915
Nestor	Swan Hunter		9 Oct, 1915		Sunk 31 May, 1916
Napier	John Brown & Company		27 Nov, 1915
Narborough	John Brown & Company		2 Mar, 1916		Wrecked 12 Jan, 1918
Narwhal	William Denny & Brothers		30 Dec, 1915		Collision 1919
Nicator	William Denny & Brothers		3 Feb, 1916
Norseman	William Doxford & Sons		15 Aug, 1916
Oberon	William Doxford & Sons		29 Sep, 1916
Observer	Fairfield Shipbuilding and Engineering Company		1 May, 1916
Offa	Fairfield Shipbuilding and Engineering Company		7 Jun, 1916
Orcadia	Fairfield Shipbuilding and Engineering Company		26 Jul, 1916
Oriana	Fairfield Shipbuilding and Engineering Company		23 Sep, 1916
Oriole	Palmer Shipbuilding and Iron Company		31 Jul, 1916
Osiris	Palmer Shipbuilding and Iron Company		28 Sep, 1916
Paladin	Scotts Shipbuilding and Engineering Company		27 Mar, 1916
Parthian	Scotts Shipbuilding and Engineering Company		3 Jul, 1916
Partridge	Swan Hunter		4 Mar, 1916
Pasley	Swan Hunter		15 Apr, 1916
Plucky	Scotts Shipbuilding and Engineering Company		21 Apr, 1916
Portia	Scotts Shipbuilding and Engineering Company		10 Aug, 1916
Pheasant	Fairfield Shipbuilding and Engineering Company		23 Oct, 1916	10 Nov, 1916	Mined 1 Mar, 1917
Phoebe	Fairfield Shipbuilding and Engineering Company		20 Nov, 1916
Pigeon	Hawthorn Leslie & Company		3 Mar, 1916
Plover	Hawthorn Leslie & Company		3 Mar, 1916
Penn	John Brown & Company		8 Apr, 1916
Peregrine	John Brown & Company		29 May, 1916
Pelican	William Beardmore & Company		18 Mar, 1916
Pellew	William Beardmore & Company		8 May, 1916
Petard	William Denny & Brothers		24 Mar, 1916
Peyton	William Denny & Brothers		2 May, 1916
Prince	Alexander Stephen & Sons		26 Jul, 1916
Pylades	Alexander Stephen & Sons		28 Sep, 1916
Medina	J. Samuel White		8 Mar, 1916
Medway	J. Samuel White		19 Apr, 1916
Mastiff	John I. Thornycroft & Company		5 Sep, 1914
Meteor	John I. Thornycroft & Company		24 Jul, 1914
Michael	John I. Thornycroft & Company		19 May, 1915
Milbrook	John I. Thornycroft & Company		12 Jul, 1915
Minion	John I. Thornycroft & Company		11 Sep, 1915
Munster	John I. Thornycroft & Company		24 Nov, 1915
Nepean	John I. Thornycroft & Company		22 Jan, 1916
Nereus	John I. Thornycroft & Company		24 Feb, 1916
Patrician	John I. Thornycroft & Company		5 Jun, 1916
Patriot	John I. Thornycroft & Company		20 Apr, 1916
Rapid	John I. Thornycroft & Company		15 Jul, 1916
Ready	John I. Thornycroft & Company		26 Aug, 1916
Miranda	Yarrow & Company		27 May, 1914	Aug, 1914
Minos	Yarrow & Company		6 Aug, 1914
Manly	Yarrow & Company		12 Oct, 1914
Moon	Yarrow & Company		23 Apr, 1915
Morning Star	Yarrow & Company		26 Jun, 1915
Mounsey	Yarrow & Company		11 Sep, 1915
Musketeer	Yarrow & Company		12 Nov, 1915
Nerissa	Yarrow & Company		9 Feb, 1916
Relentless	Yarrow & Company		15 Apr, 1916
Rival	Yarrow & Company		14 Jun, 1916
Mansfield	Hawthorn Leslie & Company		3 Dec, 1914
Mentor	Hawthorn Leslie & Company		21 Aug, 1914

Electric Logs

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

Machinery

Generators

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

Performance

Admiralty M

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

Knots	Tons / hour	Endurance (hours)	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.

Knots	Tons / hour	Endurance (hours)	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.

Knots	Tons / hour	Endurance (hours)	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

Armament

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. There were 120 rounds per gun: 36 common, 84 lyddite, an an additional 19 practice rounds.

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."

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.

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.

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.

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. The first six ships were to complete with H.A. pompoms, and the others to receive theirs as they became available.

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

Torpedoes

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

• two 21-in D.R. Mark III torpedo tubes on the centreline (2x2) enjoying 50° arcs centered on the beam.

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

Other Weapons

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

Fire Control

Range and Order Instruments

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.

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:

• one Waymouth-Cooke sextant rangefinder
• one Vickers Range Clock
• one Dumaresq
• range and deflection receivers at each gun

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.

Directors

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

Torpedo Control

Fire Gong and Lamp Reply Circuits
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.

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.

Electrical Instruments
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.

Alterations

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.

See Also

• Medea Class Destroyer (1914)
• Wikipedia

Bibliography

• Gray, Randal (editor) (1985). Conway's All the World's Fighting Ships 1906–1921. London: Conway Maritime Press. (on Amazon.com and Amazon.co.uk).
• Admiralty, Technical History Section (1920). The Technical History and Index: Alteration in Armaments of H.M. Ships during the War. Vol. 4, Part 34. C.B. 1515 (34) now O.U. 6171/20. At The National Archives, Kew, United Kingdom.
• March, Edgar J. (1966). British Destroyers: A History of Development, 1892-1953. London: Seeley Service & Co. Limited. (on Bookfinder.com).