M Class destroyers (1914)

The M Class destroyers (1914) were entering service at the outbreak of the First World War, and their design became the basis of many of the war emergency destroyers, starting with the Repeat M class boats. The original M class boats spent 1915-1917 operating with the Harwich Force, before joining the Dover Patrol, where most of them spent the rest of the war.

HMS Manly from the left HMS Manly from the left

The L class destroyers of the 1912-13 programme were expected to reach 29 knots, but in the spring of 1912, before any of them had been launched, news reached Britain that the most recent German destroyers were already faster. This was mainly because they carried out their trials with a much lower load of supplies and fuel than their British equivalents, and partly because of a greater emphasis on maximum theoretical speed rather than seaworthiness, so the Admiralty believed that the L class ships would probably be faster in actual service. The German boats were probably the new V1 class and G 7 class, which were smaller than the previous generation of German destroyers, and much smaller than their British rivals, and were indeed rather lacking in seaworthiness.

However at time this wasn’t clear, and there was a real fear that the newest British destroyers might already be obsolete before they had even been launched. In June 1912 Winston Churchill, then in his first spell as First Lord of Admiralty, wrote to the Controller of the Navy and the First Sea Lord demanding destroyers that could reach 36 knots. Speed of construction was also emphasized, as war with Germany was becoming increasingly likely (in the same letter Churchill referred to ‘13-14 TPDs that might need to be started early’.

HMS Mastiff (D66) from the front HMS Mastiff (D66) from the front

The Controller of Navy was willing to work towards higher speed, but not at the cost of a reduction in strength, displacement or seaworthiness. Work began on a new design that was expected to be ready to be put out to tender in mid-November 1912, six months earlier than normal. The new ships would carry the same three 4in guns and two 21in torpedo tubes as the L class (soon modified to four torpedo tubes in two double mounts). The middle gun was to be carried on a platform between the rear two funnels.  Some work went into increasing the top speed with a full load, and it was estimated that this would require ships with a length of 275ft and 33,000shp, an increase from 24,500shp in the L class.

This plan was soon abandoned. On 14 August the DNC and Controller decided to achieve the higher trials speed by reducing the weight that was required to be carried on trials to a level similar to that used by the Germans. This would allow a 265ft long destroyer to make 34 knots at 25,000shp. This became the basis of the Admiralty design. However in service the M class ships do appear to have been quicker than the L class. At Jutland the M class destroyers were able to steam at 30 knots, while the L class could only manage 26-28 knots, making them no quicker than the battlecruiser fleet.

HMS Minos (H81) from the left HMS Minos (H81) from the left

The first legend and sketch design were ready by September 1912 and it was finalised in March 1913. They would have three boilers, each with its own funnel. The middle gun would be carried between the two rear funnels. They were all three shaft ships. The design drawings were complete by 8 September 1913. This Admiralty M class became the basis of some ninety destroyers, including most of the early war emergency boats.

The original plan was to order nine Admiralty class ships and six specials (see below), a total of 15 M class destroyers. The Controller wanted to order two from John Brown, two from Palmers, two from Swan hunter one from Denny and one from White. This was soon reduced to six – three from John Brown, one from Swan Hunter and two from Palmers. White and Denny both lost out.  The money saved was used to buy the first batch of destroyer leaders.

Although Churchill had wanted to order ships ahead of schedule, his budget didn’t allow for that. However Thornycroft offered to build ships to an Admiralty design ‘on spec’, on the understanding that they would be the first to be purchased with the 1913-14 budget. Churchill approved the plan on 17 July, and two ships each were ordered from Thornycroft, Yarrow and White (later replaced by Hawthorn Leslie). The remaining ships in the class could be ordered from any of the destroyer builders, to either the ‘special’ designs or the Admiralty design.

The Admiralty issued basic specs for the ‘specials’. They were based on a 275ft long design, capable of 35 knots at full power for eight hours with 150 tons of oil. They were to be armed as the rest of the class. The price was agreed by August 1912

Thornycroft produced a 265ft long boat with four boilers and three funnels, producing 26,500shp.

HMS Miranda (D24) from the right HMS Miranda (D24) from the right

Hawthorn Leslie’s design was 265ft long, had four boilers and four funnels, producing 27,000shp.

Yarrow’s design was 260ft 3in long, had three boilers and two funnels, with the first two boilers trunked into the first funnel, which could thus be placed further back from the bridge than normal. It’s machinery produced 23,000shp.

All three designs had twin screws. The first six were officially purchased in March 1913, and a third Yarrow boat in May.

Another four boats, very similar to the M class, were ordered by Greece in 1913, but hadn’t been delivered at the outbreak of war in 1914. They were taken over by the Navy as the Medea class. 

By June 1914 the entire class was in service, and all thirteen had been brought together in the Tenth Destroyer Flotilla at Harwich, along with HMS Medea¸ which had been under construction for Greece and was taken over by the Royal Navy at the outbreak of war

The M class boats were the first destroyers to be given a rangefinder, either a one meter coincidence rangefinder (a meter long tube with a lenses at either end, using the different angles to the target from each lens to calculate the range) or a Weymouth Cooke sextant rangefinder (suitable for use on smaller ships). They were also given a Dumaresq table, a system for estimating the rate of change of range and a Vickers Clock. The chart house under the bridge was extended to one side to provide a protected space for the instruments. This system proved to be a success, and in July 1916 it was decided to install it on the older boats of the K and L class. In November this was extended to the Tribal (F) and later classes.

Late in 1916 torpedo controls were installed on the bridge, to allow the captain to directly control them. They were also given direction gun directors, again installed on the bridge, in an attempt to improve the accuracy of long range gunnery.  

In August 1916 the Navy adopted a policy for anti-aircraft guns. The M class ships were to be given a single 2-pounder pom-pom.

Service Record

The first members of the M Class entered service late in 1914. By November Meteor had joined the 1st Flotilla and Miranda the 3rd Flotilla, and both briefly served as the flagship of the second in command of their flotilla. By January five members of the class had joined the 3rd Flotilla, but by this point it had been decided to move the entire class to the 10th Flotilla, part of the Harwich Force. By March nine members of the class with the 10th Flotilla, and by June the entire class had joined it.

The entire class remained with the 10th Flotilla for all of 1915 and 1916 (apart from the Mastiff, which spent January 1916 with the 11th Submarine Flotilla but was back with the 10th by February). At first the flotilla only contained the original M class boats, but towards the end of this period a number of the wartime repeat M class destroyers also joined it.

In the spring of 1917 the class began to move to the 6th Destroyer Flotilla at Dover. Mentor, Meteor and Morris made the move by January 1917 and the entire class was at Dover by July (alongside a number of repeat M class boats). All but one member of the class remained with the 6th Flotilla almost to the end of the war, the one exception being the Minos, which moved to the North Division of the Coast of Ireland Station early in 1918.

Right at the end of the war five of the M class destroyers (Mansfield, Milne, Miranda, Moorsom and Murray) were amongst a group that were sent from Dover to form a new Twenty-First Destroyer Flotilla in the Grand Fleet. Part of the flotilla was present at the surrender of the German High Seas Fleet. The flotilla didn’t survive long into 1919, and the five M class ships were soon back in the south, most returning to Dover while Miranda went to the Nore.

The entire class survived the war, but they were worn out and many newer destroyers were now available, so they were soon removed from the fleet, and had all been sold for scrap by the end of 1921.

This relatively simple and neat history doesn’t of course tell the full story. As with most destroyers, these ships found themselves temporarily assigned to duties all around the British coast. Two fought at Jutland while serving with the Battlecruiser Fleet. Most were detached to Dover for several months at the start of 1917 before officially joining the Sixth Flotilla.

Displacement (standard)

Admiralty design: 900t
Hawthorn Leslie: 1,055t
Thornycroft boats: 980t
Yarrow boats: 850t

Displacement (loaded)

Admiralty design: 1,100t
Yarrow boats; 990t

Top Speed

Admiralty boats: 34 knots
Hawthron Leslie, Thornycroft and Yarrow boats: 35 knots


3-shaft Parson turbines (most Admiralty)
3-shaft Brown-Curtis turbines (Milne, Moorsom, Morris)
4 Yarrow boilers, 25,000shp

Hawthorn Leslie boats:
2-shaft Parsons independent reduction turbines
4 Yarrow boilers

Thornycroft boats:
2-shaft Parsons independent reduction turbines
4 Yarrow boilers

Yarrow boats:
2-shaft Brown-Curtis turbines




273ft 4in oa (Admiralty)
271ft 6in oa (Hawthorn Leslie)
274ft 3in oa (Thornycroft)
269ft 6in oa (Yarrow)


26ft 8in (Admiralty)
27ft (Hawthorn Leslie)
27ft 3in (Thornycroft)
25ft 7.5in (Yarrow)


Three 4in/ 45 QF Mk IV guns
Two 1-pounder pom pom guns
Four 21in torpedo tubes with four torpedoes

Crew complement


Ships in class

Admiralty designs
HMS Matchless
HMS Murray
HMS Myngs
HMS Milne
HMS Moorsom
HMS Morris

Hawthorn Leslie specials
HMS Mansfield
HMS Mentor

Thornycroft specials
HMS Mastiff
HMS Meteor

Yarrow specials
HMS Miranda
HMS Minos
HMS Manly


British Destroyers From Earliest Days to the Second World War, Norman Friedman. A very detailed look at the design of British destroyers from their earliest roots as torpedo boat destroyers, though the First World War and up to the start of the Second World War, supported by vast numbers of plans and well chosen photographs [read full review]
cover cover cover

Books on the First World War | Subject Index: First World War

How to cite this article: Rickard, J (19 January 2023), M Class destroyers (1914), http://www.historyofwar.org/articles/weapons_m_class_destroyer_1914.html

Help - F.A.Q. - Contact Us - Search - Recent - About Us - Privacy