HMS Mastiff (1914)

HMS Mastiff (1914) was a Thornycroft special M class destroyer that briefly served with the 1st then 3rd Flotillas after entering service, then with the 10th Flotilla at Harwich from 1915-1917 (apart from a brief spell with the 11th Submarine Flotilla), then the 6th Flotilla at Dover for the rest of the war. She fought at the battle of Dogger Bank and took part in the Ostend raid in 1918.

The Mastiff was laid down at Thornycroft on 24 July 1913, launched on 5 September 1914 and completed in November 1914. The Thornycroft Specials had four boilers and three funnels, while the standard Admiralty design had three of each.

In November 1914 she was part of the First Flotilla, which now contained nineteen I class boats and three new M class boats.

On 13 November the Admiralty ordered the M class destroyers not to move north as they became available, but instead to go to Harwich. When the order was issued Minos and Mastiff were at Portland.


In January 1915 she was part of the Third Destroyer Flotilla, part of the Grand Fleet, and under the command of the Commodore (T), but was about to join the Tenth Flotilla.

HMS Mastiff (D66), Rosyth, 1919 HMS Mastiff (D66), Rosyth, 1919

At the battle of Dogger Bank of 25 January 1915 the Tenth Flotilla contained the Aurora, Meteor, Miranda, Milne, Mentor, Mastiff, Minos and Morris, organised into a single ‘M’ Division. All eight were awarded a battle honour for Dogger Bank.

On 19 February 1915 in a report on the status of the Harwich destroyers the Meteor and Mastiff were listed as being defective and at Southhampton, presumably for repairs.

From March 1915 she was listed as part of the Tenth Destroyer Flotilla, part of the Harwich Force. She remained part of the Tenth Flotilla until March 1917, apart from a brief period detached to the Ninth Submarine Flotilla in January 1916.

On 27 March Laurel, Liberty, Leonidas and Lucifer were sent to patrol between the Mass and the North Hinder Light Vessel, to protect the Great Eastern Railway Company steamers which were still operating on the Harwich to Rotterdam route. The destroyers spotted a submarine at 4pm on 28 March, and spent the night attempting to keep her submerged. Six M class destroyers (Mentor, Manly, Morris, Milne, Mastiff and Murray) were sent to help, but early on 29 March the entire force was recalled to deal with a possible sortie by a German battlecruiser squadron. However it was soon discovered that the battlecruisers had returned to port, so the destroyers were sent back to patrol the same area. At 8.30am on 30 March the destroyers (by now raised to a total of 22) spotted U.24, but she dived and escaped. After the destroyers returned to port the Mastiff, Moorsom, Milne and Minos were sent out to continue the hunt. They were at sea from daybreak to dusk on 31 March, but the submarine returned to Zeebrugge late on 30 March.

The patrols lasted until 5 April.

In June 1915 she was one of fourteen destroyers in the Tenth Destroyer Flotilla at Harwich, which was made up of all thirteen ships in the original M class and HMS Medea¸ which had been under construction for Greece and was taken over by the Royal Navy at the outbreak of war.

At the start of July 1915 the Tenth Flotilla (Aurora, Manly, Mansfield, Mastiff, Matchless, Medea, Mentor, Meteor, Milne, Minos, Miranda, Moorsom, Morris, Murray and Myngs) was operating from Devonport, escorting troop transports, either incoming from Canada or on their way to the Dardanelles.

She was still listed with the Tenth Flotilla in December 1915.


In January 1916 she was part of Submarine Flotilla XI, based at Blyth. She had probably only just been assigned to that duty, as she was recorded as leaving Harwich on 28 December and reaching Middlesbrough by 30 December.

She was back with the Tenth Flotilla in the February 1916 Navy List, and remained with that unit until March 1917.

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

The Mastiff was one of eight M class destroyers from the flotilla which took part in the Hoyer Raid of 24-25 March 1916. This was an attempt to use five seaplanes from HMS Vindex to attack a Zeppelin base that was believed to be at Hoyer. No such base existed, but one was found a little further inland at Tondern. No bombs were dropped on this base, and the destroyer Medusa had to be abandoned after she was rammed by the Laverock.

Early on 25 April the Manly, Meteor, Mastiff, Lightfoot and Termagant left Harwich with the cruisers Conquest, Cleopatra and Penelope in an attempt to intercept the German forces heading for Lowestoft. This flotilla sailed east at first, but when news arrived that the Germans were probably heading for Yarmouth, it turned north, and moved up the coast inside the British minefield. At 3.50am the German light cruisers were spotted, soon followed by the battlecruisers. The Commodore (T) turned south, in the hope that the Germans would follow, but at first they didn’t, and instead focused on the bombardment of Lowestoft. The British turned back north to keep in touch. At about 4.20 the German light cruisers had turned to the south-east, and soon after 4.30 the two forces opened fire. However the range was too long and nobody hit anything. However the German battlecruisers then came on the scene, and at 4.49 opened fire. The cruiser Conquest was hit by several 12in shells but the destroyers were largely untouched. At 4.56 the Germans turned east to begin the voyage home before the more powerful British forces heading their way could reach the scene. The Harwich force attempted to pursue, but without success, and the Penelope was torpedoed during the operation (although survived).

The Mastiff was one of seven M class destroyers that put to sea on the night of 22 July to patrol the sea lanes between Felixstowe and Holland, part of a force of two cruisers and eight destroyers. The Mastiff was in the 1st Division, which took the lead, and early in the morning ran into three German destroyers that were out in an attempt to capture some of the merchant shipping on the same route. The division opened fire for a few minutes before the Germans were able to escape under cover of rain squall and smoke screen. Later the 2nd Division caught up with the entire German force of six destroyers, but after a short chase the Germans were getting close to the minefields off Zeebrugge, so the British withdrew.

In October 1916 she was part of the Tenth Flotilla at Harwich, which now contained all thirteen of the original M class ships, the flotilla leader HMS Nimrod and the ex Greek destroyer HMS Melpomene.


In January 1917 she wasn’t listed.

The Mastiff was still assigned to the Tenth Flotilla until March 1917

By April 1917 the Mastiff had been officially transferred to the Sixth Destroyer Flotilla at Dover, and by July she had been joined by her entire class.

On 17 May the Mastiff collided with RFA Silverol.

On 30 May 1917 the Mastiff ran ashoreunder Shakespeare Cliff, Dover, but she was refloated on the following day.

In June 1917 she was part of the Sixth Destroyer Flotilla at Dover, but was undergoing a refit at Portsmouth.

On 14 August 1917 the Mastiff lost her anchor and cable while at Dunkirk.

On 2 October 1917 the Mastiff collided with HM trawler Chrysolite.

On 12 November 1917 the Mansfield and Mastiff collided bear the South Goodwin light vessel.


In January 1918 she was part of the large destroyer force at Dover.

The Mastiff was one of five destroyers that were posted to Dunkirk before the attempted Ostend raid of 23 April 1918, with the task of patrolling off Ostend during the raid itself. During the raid the Mastiff was allocated to the 23rd Sub Division of the 22nd Division.

On 6 May the Velox and Mastiff collided.

In June 1918 she was part of the Sixth Destroyer Flotilla at Dover, but was undergoing repairs.

In June and July she was listed as being paid off (presumably for those repairs), but she was back in active service by August.

On the night of 28-29 September 1918 the Mastiff, Moorsom, Melpomene, Matchless, Morris, Phoebe, Velox and Broke carried out shore bombardments and fired star shells in support of the ground forces advancing in Flanders, replacing a force of Coastal Motor Boats that had been forced back to port by weather too rough for them to cope with.

In November 1918 she was one of eighteen destroyers in the Sixth Flotilla at Dover, which had lost most of its modern boats and was mainly made up of River and Tribal class boats.

In November 1919 she was in the hands of a care and maintenance party in the Portsmouth Reserve.

The Mastiff was awarded battle honours for Dogger Bank, the Belgian Coast 1916/18 and Ostend (Zeebrugge), 23 April 1918.

Wartime Service
November 1914: On way to 1st Destroyer Flotilla
January 1915: 3rd Destroyer Flotilla
March 1915-December 1915: 10th Destroyer Flotilla, Harwich
January 1916: 11th Submarine Flotilla
February 1916-March 1917: 10th Destroyer Flotilla, Harwich
April 1917-December 1918-: 6th Destroyer Flotilla, Dover


Displacement (standard)


Displacement (loaded)


Top Speed

35 knots


2-shaft Parsons independent reduction turbines
4 Yarrow boilers




274ft 3in oa


27ft 3in


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

Crew complement


Laid down

24 July 1913


5 September 1914


November 1914

Sold for break up

May 1921

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 (14 December 2022), HMS Mastiff (1914) ,

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