Allied Warships

HMS Seahorse (98 S)

Submarine of the S class

NavyThe Royal Navy
TypeSubmarine
ClassS 
Pennant98 S 
Built byChatham Dockyard (Chatham, U.K.) 
Ordered16 Mar 1931 
Laid down14 Sep 1931 
Launched15 Nov 1932 
Commissioned2 Oct 1933 
Lost7 Jan 1940 
Loss position54° 19'N, 7° 30'E
History

Seahorse (Lt. Dennis Staunton Massy-Dawson, RN) sailed from Rosyth to patrol off Heligoland on 26 December 1939.

She was mot likely sunk after being attacked and depth charged by ships from the German 1st Minesweeping Flotilla on 7 January 1940 about 15 nautical miles north-west of Heligoland in position 54º19'N, 07º30'E.

It is also possible that she was rammed and sunk by the German Sperrbrecher IV/Oakland south-east of Helgoland on 29 December 1939 but this seem not very likely.

HMS Seahorse was never heard from after sailing from Blyth on 26 December 1939 for patrol off western Jutland. Her operational area was to be initially off Heligoland then move to the mouth of the Elbe on 30 December and return to Blyth on 9 January 1940.
A report by the German 1st M-Flotille states that a submarine was sighted at 1318 hrs of 7 January 1940, the boat dived, was located and depth charges were dropped at the location. Submarine noises were picked up on the hydroacustic listening devices, the echolocator indicated a clear echo and more depth charges were dropped. Fog prevented any sort of visual contact with possible debris being established.
The fact that the report mentions a visual contact & that no boat returning from patrol reported this attack leaves only HMS Seahorse as the target of the attack. The lack of evidence of a "kill" may just be attributed to the attack causing sufficient damage to prevent the boat from resurfacing but not wrecking the hull to the point of causing any debris to surface. 

Commands listed for HMS Seahorse (98 S)

Please note that we're still working on this section.

CommanderFromTo
1Lt. Dennis Staunton Massy-Dawson, RN15 Apr 19397 Jan 1940

You can help improve our commands section
Click here to Submit events/comments/updates for this vessel.
Please use this if you spot mistakes or want to improve this ships page.

Notable events involving Seahorse include:


The history of HMS Seahorse as compiled on this page is extracted from the patrol reports and logbooks of HMS Seahorse.

This page was last updated in December 2014.

24 Aug 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) departed Dundee to take up a patrol position to the south-west of Stavanger, Norway. When the war with Germany commenced this became her 1st war patrol.

For the daily positions of HMS Seahorse during this patrol see the map below.

(1)

5 Sep 1939
While on the return passage to Dundee HMS Seahorse (Lt. D.S. Massy-Dawson, RN) was bombed in error by a British aircraft at 2007 hours in position 56º40'N, 01º04'W. She sustained some damage which required her to dock.

Seahorse had dived when the aircraft was sighted but her after hydroplanes jammed and depth control was lost. In the meantime two depth charges were dropped by the aircraft but these caused no damage. Seahorse then broached and her bow came out of the water. A third depth charge was then dropped but this also caused no damage. Before Seahorse was able to submerge again a fourth depth charge was dropped very close which shook the submarine severely but it caused no damage. Seahorse then went down again and hit the bottom causing damage to her A/S dome. (1)

6 Sep 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) ended her 1st war patrol at Dundee.

She shifted from Dundee to Rosyth later the same day. (2)

7 Sep 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) was docked at Rosyth. (2)

11 Sep 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) was undocked. (2)

12 Sep 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) shifted from Rosyth to Dundee. (2)

16 Sep 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) departed Dundee for her 2nd war patrol. She was ordered to patrol off the south-west coast of Norway.

For the daily and attack positions of HMS Seahorse during this patrol see the map below.

(1)

17 Sep 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) fired three torpedoes against German U-boat U-36 in the North Sea in position 56°42'N, 00°52'E. No hits were obtained.

1140 hours - Sighted the conning tower of a submarine bearing 305°. Range was 11000 yards. Started attack.

1204 hours - Observed the submarine to fire two rounds with her gun, apparently at a merchant ship to the south.

1210 hours - In position 56°42'N, 00°52'E fired three torpedoes at the enemy submarine from 7000 yards. Went deep on firing and turned to the northward.

1219 hours - Heard a single heavy explosion. Remained deep.

1239 hours - Returned to periscope depth. No submarine in sight. (1)

2 Oct 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) ended her 2nd war patrol at Dundee. (1)

4 Oct 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) shifted from Dundee to Rosyth where she was immediately docked. (3)

8 Oct 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) was undocked at Rosyth. She then returned to Dundee. (3)

14 Oct 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) shifted from Dundee to Rosyth. (3)

17 Oct 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) departed Rosyth for her 3rd war patrol. She was ordered to patrol off the south coast of Norway / Skagerrak.

For the daily positions of HMS Seahorse during this patrol see the map below.

(1)

30 Oct 1939
At 2330 hours, in position 56°29'N, 01°10'W, HMS Seahorse (Lt. D.S. Massy-Dawson, RN) sighted a submarine. An attack was started but before torpedoes could be fired the submarine dived. This might have been U-13. (1)

31 Oct 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) ended her 3rd war patrol at Rosyth. (1)

9 Nov 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) departed Rosyth for Blyth. (4)

10 Nov 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) arrived at Blyth. (4)

12 Nov 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) departed Blyth for her 4th war patrol. She was ordered to patrol in the North Sea to the north-west of The Netherlands.

For the daily positions of HMS Seahorse during this patrol see the map below.

(1)

28 Nov 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) ended her 4th war patrol at Blyth. (1)

29 Nov 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) was docked at Blyth. (4)

12 Dec 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) was undocked. (5)

13 Dec 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) departed Blyth for her 5th war patrol. She was ordered to patrol off the British east coast. (5)

15 Dec 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) ended her 5th war patrol at Blyth after having been recalled. (5)

26 Dec 1939
HMS Seahorse (Lt. D.S. Massy-Dawson, RN) departed Blyth for her 6th war patrol. She was ordered to patrol in the Heligoland Bight. (1)

Sources

  1. ADM 199/1840
  2. ADM 173/16033
  3. ADM 173/16034
  4. ADM 173/16035
  5. ADM 199/373

ADM numbers indicate documents at the British National Archives at Kew, London.


Return to the Allied Warships section