HM S/M L 23

L23 the oldest of the 6th Flotilla Boats

The story of L 23 is fascinating because the boat was operational from Blyth in 1939-1940 but also returned as the principal sea training Boat in 1941-1942. Most of those wartime submariners who trained at Blyth spent some of their time day-running on L 23.

Class: L

Ordered: December 1916

Builder: Vickers up to installation of engines then completed at Chatham RN Dockyard

Laid Down: 29.8.1917

Launched: 1.7.1919

Commissioned: 5.8.1924

Pennant: N 23

L 23 layout

L 23 was one of the ‘L’ class of submarines built during the First World War. The Admiralty design derived from experience of the E class as the standard patrol submarine. L 23 was laid down at Vickers in Barrow, the engines were installed then the Boat was completed at Chatham.

Turks Yard , Chatham birthplace of L 23

238 .5’ x 23 5‘ x 16’ = 890 tons (surface)
1,080 tons (submerged)

Four 21″ bow torpedo tubes.
Eight 21″ Mark IV*S Torpedoes.
One 4″ Quick Firing Mk III gun on breastwork mounting.
90 rounds ammunition.
One Lewis gun and five rifles.

Twin Diesel engines 2,400 HP = 17.5 knots.
76 tons oil fuel = 2,380 miles @ 16 kts or 4,030 miles @ 8 kts.
1.7 tons per day on patrol.Main motors 1,600 HP = 10.5 kts submerged.
Batteries. 336 cells of 135 tons.
1.5 hrs at 9 knots submerged.
HullSaddle Tank type. Operational diving depth 150 feet but known to reach 250-300′ in service.
Complement4 Officers and 37 men.
Detection equipment

Two 30 foot periscopes
Type 118 Asdic set.

L 23 was based with the 6th Submarine Flotilla at Portland from 1937. In 1938 the boat took part in North Sea exercises with the rest of the Flotilla. During this time the Flotilla was based in the South Harbour, Blyth. At the outbreak of war the boat was serving with the 5th Flotilla at Portsmouth, engaged in training duties.

L 23 [Lt. F.J. Brooks, 30] left Blockhouse for Blyth in company with HMS Skate on 28 September 1939. The First Lieutenant at this time was the remarkable Lt. Claude Peterkin who had started his career on the lower deck. Sadly he was to die in HM S/M H49. The two warships trailed behind east coast convoy FN12, Ensigns flying. L 23 arrived at Blyth on 30 September and rejoined the Sixth Submarine Flotilla. The boat took part in exercises off Blyth between 3 and 4 October.

Patrol 1: 11 October 1939, L 23 left Blyth for her first patrol on the Dogger Bank and Zone A2, keeping to the West of the German Declared Minefield. Admiralty believed that a German raid against the British East coast was imminent. Every available submarine was sent out but the raid did not materialise.

L 23 unleashed !

L 23 arrived at Rosyth on October 16.

Patrol 2: October 21, 1939 L 23 left Rosyth for a patrol deep in the Skaggerak, Zone C2 [Skaw to Lindesnes], keeping to the North of the German Declared Minefield [GDM]. The boat returned to Rosyth on November 1.

Patrol 3: November 12, L 23 left Rosyth for a patrol West of the GDM, Zones A, A1 and A3. On 21 November the boat is off Little Fisher Bank. Scharnhorst, Gneisenau escorted by Koln, Leipzig and three destroyers all slip past the Submarine without being seen.

L 23 returned to Blyth on November 30. The Boat is in need of repair and goes into dry dock.

Patrol 4: December 14, L 23 leaves Blyth for a patrol in Zone A1 but is recalled

Patrol 5: December 17, L 23 leaves Blyth for a patrol in the Skaggerak [Zone C1] Kristiansund under Lt. Leslie Hill . This is an intelligence gathering operation to assemble information on the routes used by German maritime traffic. During this patrol L 23 broke international maritime law by patrolling inside Norwegian territorial waters to investigate Kristiansund. The Boat returned to Rosyth on December 29. The patrol ends at Rosyth because of intense German mine-laying in the Tyne and Blyth roads. The Blyth fairway is swept and next morning L 23 returns to Blyth.

The Control Room of L 23 looking aft. The rating in the foreground right is the Helmsman. Immediately behind him (seated) peering at the depth gauge is one of the men operating the hydroplanes [The face of the second hydroplane operator can be seen just behind the Captain’s back]. Immediately behind him standing is the First Lieutenant. The Captain [wearing a cap] is operating the search periscope while adjacent to him and awaiting his instructions is the outside Engine Room Artificer or ‘Outside ‘Tiffy’

P January 12 1940, L 23 left Blyth to act as escort to an incoming convoy from Bergen. The Boat returned to Blyth

Patrol 6: January 21, 1940 L 23 left Blyth for a patrol in Zone A2. The boat returned to Blyth on January 2.

Patrol 7: February 12 1940, L 23 left Blyth for a patrol in Zone A2. On February 20, at 00:55, L 23 was on the surface in poor visibility charging batteries when she was surprised by German destroyers at a range of just 700 yards. The destroyers were Wilhelm Heidkamp and Karl Galster, escorts to battlecruisers Scharnhorst, Gneisenau and the heavy cruiser Admiral Hipper. The German ships were engaged in ‘Operation Nordmark’ designed to engage HN convoys bound for Britain and if possible, intercept the Grand Fleet. The presence of these warships being guaranteed to entice the British warships out of Scapa Flow. A U-boat trap had been organised between Kinnaird Head and the Shetlands. Once certain that these German ships were at sea, VA(S) Horton set a submarine trap of his own. Seal and L 23 were dispatched to patrol North of the GDM. L 23 had only just reached the position when ‘one cruiser and two destroyers steering SE’ was reported. .

Karl Galster, tormentor of L 23

L 23 dived. The first depth charge exploded when the Boat was at 40 feet and three more followed at close intervals. When L 23 reached 80 feet the second destroyer passed overhead and also dropped four depth charges. Every motor was then stopped, following the example of Eaden during the attack on Spearfish in September 1939. Like Spearfish before her, L 23 bottomed in 152 feet of water. No more depth charges were dropped but surface craft were heard to hunt for her until 04:30 hrs. L 23 surfaced around 06:00 hours in a patch of oil which had leaked from one of the external tanks. Some sources state that Wilhelm Galster dropped nine depth charges against L 23, while other sources record the minesweepers M1, M5 and M7 carried out the attacks. Oil and bubbles were observed on the surface in sufficient quantities to convince the German warships that they had sunk another British submarine. The position of this attack was logged as 57°12’N, 05°32’E L 23 and her crew were extremely lucky to survive this attack. L 23 surfaced at 06:00 hrs in her own oil slick. The boat directly returned to Rosyth, reaching the Forth on February 21. Two days later L 23 sailed for Blyth.

L 23 7th Patrol

This time L 23 was in dock at Blyth between February 27 and March 7, 1940. The decision had been taken to finally relegate the old Submarine to training duties. There was one last patrol to carry out however.

IWM image of trainees loading torpedoes on L 23 at the Middle Jetty, Blyth in June 1942. The South Pier has been crudely removed by the censor to erase all indications of location – and possibly other visiting submarines

Patrol 8: March 25, 1940, L 23 left Blyth on her last wartime patrol, one again to Zone A2. The Boat returned to Blyth on March 24. On March 29, L 23 [Lt. C Walker] left Blyth for Portsmouth [The 5th Submarine Flotilla, Fort Blockhouse] by way of Sheerness. Following a lengthy spell of training duties at Blockhouse and later Scapa Flow, L 23 was in need of a major refit. This was carried out at the Caledon Yard in Dundee. When repairs were complete L 23 left Dundee for Blyth on 12 October 1941. L 23 [Lt. T. Barlow] became the 6th Flotilla sea training boat. L 23 remained at Blyth until April 3, 1942 when under Lt. M Lumby she left to carry out exercises at Scapa Flow. On May 1, 1942 the Boat returned to Blyth under Lt. E Turner, escorted by HMS Scalby Wyke. One again the Boat resumed sea training duties.

As L 23 was used for day running rather than operations, the fore ends was both comfortable and spacious. The men are playing naval ludo or ‘uckers’.
Stray dog ‘Whiskey’ allegedly adopted by the crew of L 23 in June 1942. During the First World War Blyth submarine crews certainly did adopt dogs, cats and budgies, though this practice was frowned on by authority in the Second War. IWM
We are told that Whiskey even had his own hammock IWM
Coxswain oversees planesman on L boat

On August 12 1942, L 23 [Lt. J. Bridger] left Blyth for the very last time. The Boat underwent a major refit at Scotts of Greenock which included being fitted with a new ASDIC set and radar equipment. L 23 was now based on the West coast of Scotland where part of her work included the training of Chariot crews. On February 13, 1943, L 23 left Britain for Canada.

L 23 was decommissioned in May 1946. She sank off Nova Scotia on her way to the breaker’s yard


ADM 173/15760, ADM 173/15761, ADM 199/1830, ADM 173/15762, ADM 173/15763, ADM 199/373, ADM 199/2560, ADM 173/373, ADM 199/400, ADM 199/1907, ADM 173/16797, ADM 173/16798, ADM 173/17280, ADM 173/17281, ADM 173/17282, ADM 173/17283, ADM 173/17284, ADM 173/17285, ADM 173/17286, ADM 173/17287, ADM 199/1834, ADM 173/17288, ADM 173/17289, ADM 173/17290, ADM 173/17291, ADM 173/17836, ADM 173/17837, ADM 173/17838, ADM 173/17841, ADM 173/17842, ADM 173/17843, ADM 173/17844

Staff History Submarine Operations 1939-45 Vol 1

Hezlett, British and Allied Submarine Operations

BR3043, IWM

© P Armstrong