1 Sep, 1940
At 0150 hours HMS Tuna (Lt.Cdr. M.K. Cavenagh-Mainwaring, RN) fires torpedoes at ' what is identified as ' a submarine in the North Sea about 175 nautical east of Dundee, Scotland in position 56º09'N, 02º15'E. All torpedoes fired missed their target. (see map)

22 Sep, 1940
HMS Tuna (Lt.Cdr. M.K. Cavenagh-Mainwaring, RN) torpedoes and sinks the German merchant Tirrana (7230 GRT, former Norwegian Tirrana (offsite link) in the Bay of Biscay south of the Gironde estuary, about 15 nautical miles south-west of Soulac-sur-Mer, France in position 45º19'N, 01º20'W.

Tirranna was captured by the German armed merchant cruiser Atlantis in the Indian Ocean about 675 nautical miles east-south-east of Port Louis, Mauritius in position 22º40'S, 69º20'E on 10 June 1940. (see map)

24 Sep, 1940
HMS Tuna (Lt.Cdr. M.K. Cavenagh-Mainwaring, RN) torpedoes and sinks the German catapult ship Ostmark (1281 GRT) in the Bay of Biscay about 35 nautical miles south-west of St. Nazaire, France in position 47º01'N, 03º02'W. (see map)

18 Dec, 1940
At 0430 hours HMS Tuna (Lt.Cdr. M.K. Cavenagh-Mainwaring, DSO, RN) attacks the Italian submarine Brin with torpedoes and gunfire in the Bay of Biscay about 55 nautical miles east of the Gironde estuary in position 45º28'N, 02º27'W. The Italian submarine escapes unharmed.

At 2314 hours HMS Tuna sinks the French tug Chassiron (172 GRT) with gunfire about 25 nautical miles west-south-west of the Gironde estuary in position 45º28'N, 01º38'E. (see map)

10 Jul, 1941
While on patrol in the Bay of Biscay HMS Tuna (Lt.Cdr. M.K. Cavenagh-Mainwaring, DSO, RN) fires two torpedoes at a submerged Asdic contact stearing approximate course 191, of what is thought to be an enemy submarine in position 46º00'N, 09º40'W. The torpedoes misses their target. No Axis submarines were however reported to be near that position at that date, so that attack was most likely against a non-sub target (if any). (see map)

19 Jul, 1941
HMS Tuna (Lt.Cdr. M.K. Cavenagh-Mainwaring, DSO, RN) fires 6 torpedoes at the German tanker Benno (8306 GRT, former Norwegian Ole Jacob, offsite link) escorted by the German minesweepers M 18, M 25, M 27 and M 30 60 nautical miles north-west of the Gironde estuary. Although six detanations were heard all torpedoes missed their target(s).

The Ole Jacob was captured on 10 November 1940 by the German armed merchant cruiser Atlantis in the Bay of Bengal in position position 06º30'N, 90º13'E.

7 Dec, 1942
HMS Tuna (Lt. R.P. Raikes, DSO, RN) delivered the "Cockleshell Heroes" to the mouth of the Gironde for their daring raid on Bordeaux, France in which 6 German ships were mined. The raid was called Operation Frankton, and only two of the 12 men returned.

7 Apr, 1943
The German submarine U-644 was sunk in the North Sea north-west of Narvik, Norway, in position 69º38'N, 05º40'W, by torpedoes from the British submarine HMS Tuna (Lt. D.S.R. Martin, RN). (see map)

14 Apr, 1943
HMS Tuna (Lt. D.S.R. Martin, RN) attacks the German submarine U-302 with 4 torpedoes south of Jan Mayen Island. The torpedoes however miss their target.