THE BRITISH BECAME INVOLVED IN NORWAY as a result of their determination to stop the Swedish iron ore traffic with Germany, as well as to hinder the use of the Norwegian inner leads as a route to the open sea to and from Germany which avoided our blockade. After failing to get Norway to co-operate by diplomacy and failing to secure Narvik and the oil fields by measures with the outward appearance of giving help to the Finns, they had decided to lay mines in Norwegian territorial waters. Although this would violate Norwegian neutrality it would force all traffic out to sea where it could be made subject to our contraband control. This move was to be justified to the world by insisting that the present situation unfairly favoured Germany and could no longer be tolerated. It was accepted that this action might provoke a German invasion of Norway and so it was an integral part of the plan to have troops ready to forestall them at Narvik, Trondheim, Bergen and Stavanger. British submarine patrols were to be stiffened in the Skagerrak and the Heligoland Bight as a cover for these operations, which were scheduled for 4th April.

On lst April, VA(S) summoned his flotilla commanders to a conference at Northways in which he briefed them about 'Plan R4', as the minelaying off the Norwegian coast and the military operations which were part of it, were called. He told them that the minelaying was likely to lead to the German invasion of Norway, as the iron ore traffic was vital to them¹. He therefore intended to send every available submarine to patrol in the Skagerrak and east of the German declared area by dawn on 5th April. He also intended to place submarines off likely landing places in Norway. At the time of the conference there were only three submarines on patrol, Triton was off the Skaw, Trident off Arendal and Swordfish off the north west point of Denmark². Sealion sailed the same day to join them and on 2nd April, Orzel, Sunfish and Unity put to sea. Narwhal also sailed on 2nd April to lay the first British submarine minefield of the war. This had been planned earlier as a way to hinder the iron ore traffic at its German end when the Baltic entrances were frozen. Narwhal (Lieutenant Commander RJ Burch RN) embarked 50 mines at Immingham and laid them on 4th April fifty miles northwest of Heligoland where there was believed to be an exit into the open sea. This field sank the German anti-submarine vessel Emden but did not catch any iron ore ships. On 4th April the minelaying off the coast of Norway was postponed until 8th April and this respite allowed five more submarines to be sent to sea. At the same time, some submarines already at sea were moved further into the Skagerrak and Kattegat⁵. Late on 4th April VA(S) sent out an order that transports were to be attacked rather than warships. On 4th and 5th April, Trident, who had left harbour before the Norwegian invasion scare and knew nothing about it, stopped and examined several neutral ships off the Lister Light. On 5th April too, Unity attacked and missed a U-boat in the Heligoland Bight. On 6th April VA(S) told Sealion, in the Kattegat, not to compromise her position by examining merchant ships. She was well placed to intercept an invasion force but was in a difficult position. It was flat calm and very shallow and seawater of low density caused trimming problems. There were also many fishing vessels about.

French submarines, designated in the British order of battle as the Tenth Submarine Flotilla, had now reinforced the British submarines in the North Sea. They were stationed at Harwich where they arrived on 23rd March. It consisted initially of the depot ship Jules Verne and the submarines Sybille, Amazone, Antiope and Doris. Later in the month it was reinforced by Calypso, Circe, Sfax and Thetis. Later still Achille, Orphee, Pasteur, Casabianca and Rubis arrived. One of its submarines, Sybille, had already been sent to patrol off Terschelling and Antiope and Amazone took over patrols west of the German declared area. There were now sixteen British, French and Polish submarines at sea ready to oppose any German counter measures to the British minelaying in Norwegian waters on 8th April.

The German invasion, when it came, was nothing to do with the British minelaying in Norwegian waters, which they did not even know was in progress. The enemy's plans stemmed from the German Navy's strategic appreciation that they would never achieve much in a maritime war with Great Britain while they remained bottled up in the Baltic and the Heligoland Bight with limited access to the oceans. They realised that if they possessed Norway, the situation would be enormously improved. The invasion of Norway appealed to Hitler anyway as he saw himself as head of all the 'Nordic' races. A proposal to seize Norway had been put forward by the German Navy in October 1939 and planning was authorised during the winter of 1939 - 1940. Hitler, worried by intelligence reports of allied 'volunteers' for Finland and by the British disregard for Norwegian neutrality during the Altmark incident, authorised the operation to go ahead with a date in late March for the landings. The aim of the operation was to prevent the British gaining a foothold in Scandinavia or the Baltic, to ensure that supplies of Swedish iron ore were uninterrupted and to give both the German Navy and Air Force a closer and wider base for operations. The date, however, had to be put back as the ice in the Baltic was slower than usual in melting.

A tanker with no ensign or distinguishing marks then left territorial waters to cut a corner across a bay. After watching her pass and examining her closely through the periscope, Trident surfaced and ordered her to stop¹³. This she did and at once, abandoned ship and scuttled herself. Trident hastened her end with a torpedo and took the Captain prisoner leaving her crew in the ship's boats. This was Posidonia of 8036 tons bound for Bergen full of oil fuel¹⁴. Among these ships heading north in territorial waters was Orion; the second of the German armed merchant raiders that sailed on 6th April. No British forces detected her although she passed through the waters where the Home Fleet was operating against the German battle cruisers.

While Rio de Janeiro and Posidonia were being sunk by Orzel and Trident, VA(S) was discussing his dispositions with the Admiralty. The Admiralty approved of them in general, but still believing that they had to deal with a break out by the German heavy ships rather than an invasion of Norway, instructed him to withdraw submarines from off Norwegian ports and place them between southwest Norway and the north of the German declared area to intercept them on their return. Thistle was ordered to patrol off Utsira and Clyde off Jaederens, Tarpon to the north of the declared area and Sealion, already in the Kattegat, off the entrance to the Sound. Orzel's report of the sinking of Rio de Janeiro then came in as well as a report from our Naval Attaché at Copenhagen that Gneisenau or Blucher with two cruisers and three destroyers had passed the Langland Belt at dawn, heading north. Seal, Truant and Orzel were at once ordered to patrol on the parallel of 57 50'N in the Skagerrak to intercept should this new force sortie and join the main German units now in the vicinity of Trondheim. The force in the Kattegat in fact consisted of Blucher, Lutzow, Emden and three torpedo boats and was bound for Oslo with 2000 troops. It had left Swinemunde the previous evening. Sealion did not sight them as they emerged from the Belts as she was by now off the Sound. The force was, however, sighted just inside the Skaw by Triton (Lieutenant Commander EF Pizey RN) who at 1758 fired a full salvo of ten torpedoes at long range (7500 yds) at Blucher. The German force increased speed while the torpedoes were running and all missed astern¹⁵. Sunfish (Lieutenant Commander JE Slaughter RN) also sighted this force at 1850 but was too far off to attack. Both submarines were able to surface and make enemy reports as soon as it was dark. Unfortunately Trident, originally off Oslo Fjord, had been moved to patrol off Larvik as it was thought likely that the German ships would land their troops there rather than face the formidable coastal defences in the approaches to Oslo¹⁶. Trident did not therefore sight the enemy force when it entered Oslo Fjord just before midnight.

During 8th April, three more groups crossed from the German North Sea bases to Norway. The largest group consisting of the light cruisers Koln and Konigsberg, the sloop Bremse and an E-Boat flotilla with 1500 troops left Wilhelmshaven in the evening of 7th April for Bergen. A smaller group consisting of the sloop Brummer and two torpedo boats with 500 troops left Cuxhaven at the same time for Stavanger. These groups avoided Unity, still the only British submarine east of the declared area and also Spearfish further north and Truant off Egersund, and landed their troops unmolested. The last invasion group consisting of the light cruiser Karlsruhe with Tsingtau, Grief, destroyers and another E-boat flotilla with 1230 troops left the Weser early on 8th April for Kristiansand and Arendal. Finally four minelayers left Cuxhaven for Egersund to lay the minefield across the entrance to the Skagerrak. Not one of these groups was intercepted by any of our submarines, probably because B-dienst, the German radio interception service, revealed their positions to them. The first two sections of the German Skagerrak mine barrage were laid on the night of 8th/ 9th April by the minelayers Roland, Cobra, Preussen and Konigen Louise and the last sections on 11th - 13th April.

The Norwegian Navy possessed nine submarines but they were small and elderly. They were similar in size to our H-class and were armed with the small eighteen-inch torpedo. Since 1939, all had been commissioned and were disposed round the coast to ensure that Norway's neutrality was not violated. One (B4) was refitting at Carljohansvern in Oslo Fjord and the three oldest (A2, A3 and A4) were stationed at the submarine base at Teie also in Oslo Fjord. B2 and B5 were at Gravene near Kristiansand to guard the Skagerrak coast. B6 was at Flatoy near Bergen and B1 and B3 were at Liland on the north side of Ofot Fjord near Narvik. When the German invasion occurred, all the submarines were in harbour but with orders to put to sea at dawn on 9th April. The boats in Oslo Fjord put to sea accordingly but did not see the German ships, which had already passed. A2 tangled with two German minesweepers and was forced to the surface while A3 and A4 patrolled the lower part of Oslo Fjord. B4 was towed away from the dockyard to the upper part of Oslo Fjord. On the south coast B2 and B5 put to sea from Gravarne but missed the invading force in low visibility when it entered Kristiansand. Aircraft harassed both and B5 was machine gunned while submerged and lay on the bottom for some hours. B2 had to return to harbour with defects. In the Bergen area B6 put to sea from Flatoy and patrolled off Byfjorden but sighted nothing more than two E-boats. The sailing of B1 and B3 in the Narvik area was cancelled by the local senior officer because of reports of the laying of a British minefield by surface forces, and therefore did not intercept the German destroyers when they arrived.

By the forenoon of 9th April, even the Admiralty realised that Norway was being invaded for it was reported in the morning papers. Nevertheless they still seemed more interested in intercepting the German ships off Norway as they returned than in preventing further invasion. VA(S) then ordered Thistle back to Stavanger and Truant to Oslo and told Clyde and Seal to close the coast of Norway and sink any German ships they could find. Thistle (Lieutenant Commander WF Haselfoot RN) sighted a small U-boat off Skudenes but missed her with six torpedoes. She was told to close Stavanger and attack any ships there but when she signalled that she would comply next day but she had only two torpedoes left, she was ordered to resume patrol off Skudenes. Here early next morning U4, which she had missed the day before, caught her on the surface while charging her batteries and torpedoed and sank her. She was lost with all hands including her Commanding Officer, Lieutenant Commander WF Haselfoot RN, four other officers and 48 men. Trident was invited to dive into Oslo Fjord but was at the time too pre-occupied with German anti-submarine trawlers off the entrance to comply. Unity (Lieutenant JFB Brown RN), off Horns Reef, also on 9th April, was attacked with depth charges by what she described as a merchant ship but was probably an auxiliary anti-submarine vessel¹⁵.

The Norwegian B1 and B3 were the only submarines in the Narvik area when the Germans arrived and they were hampered by bad visibility and later by German antisubmarine craft. They also suffered from a lack of operational control in the area. Consequently they saw nothing of either the first or second battles of Narvik. B1 returned to Liland but then a German trawler appeared and she bottomed in very shallow water (8 metres). It was later decided to abandon her on the bottom and the crew withdrew overland to Tromso. B3, however, penetrated beyond Narvik and sighted two German destroyers off Ramsund. She thought she had been detected by them and withdrew to the Vestfjord where contact was made with the British at Skelfjord in the Lofotens. The British, however, were mainly interested in keeping the Norwegian submarines out of the way of their anti U-boat operations in the area.

German strategy at this time was to concentrate all sea traffic on the route across the Skagerrak to Oslo. No supplies were to be shipped by sea to the western ports of Norway. Every effort was to be made to escort the traffic to Oslo and to hunt submarines in the Skagerrak and Kattegat. It was also intended to reinforce the minefield between Egersund and Hantsholm. The German anti-submarine measures in the Skagerrak were now therefore increasing and Spearfish (Lieutenant Commander JH Forbes RN) on her arrival close north west of the Skaw at 1730, was hunted and 66 depth charges were dropped. She had, in fact, been caught up in the counter attack on Triton after her attack on the convoy. Spearfish was counter attacked again at 2005 damaging the after periscope. At 2015 the hunters were still in contact and the battery was low and the air getting foul. However she had shaken them off by 2330 and after being down for twenty hours, she was able to surface and withdraw to seawards. She had only been on the surface for half an hour when she sighted a large ship approaching at high speed from the northwards. She fired six torpedoes by eye at 0033 hitting the target aft with two torpedoes. Spearfish then made off on the surface at her best speed to the westwards. This was the pocket battleship Lutzow returning to Germany from Oslo. She was left drifting with both propellers blown off and rudder jammed and with a list and slowly sinking. Four torpedo boats and some patrol craft came to her assistance and she was taken in tow by a Danish tug but ran aground on a sandbank. Sealion was ordered to intercept but the water was very shallow and she had only one fathom under her keel at periscope depth. Lutzow was not seen by Sealion and was not refloated until the early morning of 12th April and arrived at Kiel later the same day. She was under repair until April 1941 and missed a planned sortie into the Atlantic.

On the morning of 11th April, of the large German warships that had taken part in the invasion of Norway, four were still at sea. Scharnhorst and Gneisenau were in company north of the Faeroe Islands, Hipper was well out to sea west of Trondheim and all three were now heading south. Koln was steaming down the east side of the German declared area in the North Sea. Having left Bergen she had hidden for the night in a fjord as units of the Home Fleet were reported and then made a dash for it and reached Wilhemshaven safely after passing to the west of all our submarines on patrol. She may well have known their positions from radio intelligences.

Early on 11th April Triad (Lieutenant Commander ERJ Oddie RN) off Oslo Fjord, sank Ionia of 3102 tons at a range of 1000 yards with one hit out of two torpedoes. Later the same day, Sealion (Lieutenant Commander B Bryant RN) sank August Leonhardt of 2600 tons in the Kattegat south of Anholt, scoring one hit out of two torpedoes fired at 2700 yards. The nights were already getting shorter giving only four hours to re-charge batteries, which was scarcely enough after running submerged for twenty hours or so. This was especially difficult as the weather had cleared and visibility was now good. VA(S) made a number of redispositions during the day. Triton, with no torpedoes left, was ordered back to Rosyth and Trident too as she had been at sea since 25th March although she still had twelve torpedoes on board. Orzel was moved to the Swedish coast, Shark and Seawolf moved eastwards and Tarpon ordered into the Heligoland Bight. The Government also lifted its restrictions still further and the sink at sight policy was permitted anywhere within ten miles of the Norwegian coast south of 61N and east of 6E as far down as 54N.

During the night, the German main units passed southward at high speed between Norway and the Shetlands. By 0830 on 12th April, Scharnhorst and Gneisenau had met Hipper and shortly afterwards the whole force was sighted and reported by a Coastal Command aircraft. The weather, however, was very bad with rain, snow and sleet and poor visibility so that large striking forces from Bomber Command were unable to find the ships. A glance at Map 8 shows the disposition of submarines at the time. No less than seven boats were in the Heligoland Bight or east of the declared area, and six more were in the Kattegat. Another four were in the Skagerrak or on passage north of the declared area. Strenuous efforts were made to intercept the German ships. At 0900 VA(S) ordered Trident and Severn to patrol on latitude 5750'N in the middle of the Skagerrak, and Spearfish, Sunfish and Snapper to close the Skaw while Shark patrolled east of the northern edge of the declared area. These dispositions were designed to intercept the enemy should he go home through the entrance to the Baltic. Later in the day, Tarpon, Shark and Seawolf were ordered to intercept should the enemy double back from the Skaw towards Heligoland. The enemy, however, had already destroyed Tarpon. On 10th April she had attacked the German ship Schiff 40 northeast of the German declared area. Her two torpedoes missed and her periscope was sighted and she was heavily counter attacked and sunk with depth charges. Schiff 40 remained in the vicinity for twenty-two hours and made a number of other attacks. She went down with all hands on this her first patrol, her Commanding Officer (Lieutenant Commander HJ Caldwell RN), four other officers and 48 men being lost.

On 15th April, Taku (Lieutenant Commander VJH Van Der Byl RN) arrived to establish patrol off Fro Havet, the northern entrance to Trondheim Fjord. However she was soon ordered south to keep out of the way of units of the Home Fleet. In the Skagerrak, Snapper still on the surface in the early morning before it was light attacked what she believed to be a convoy and at once dived. She fired four torpedoes and all four were heard to hit. They sank M1701 ( Jan Behrens of 525 tons) and M1702 (C Jansen of 472 tons) but they were minesweepers not supply ships. Snapper was counter attacked for an hour but managed to steal away and made an enemy report. She was hunted all next day and depth charges were dropped. She broke contact at dusk and made for her base with all torpedoes expended. Shark (Lieutenant PN Buckley RN), off the south coast of Norway in the afternoon of 15th, fired five torpedoes at two transports escorted by Brummer, but the range was long (4000 yards) and the enemy saw the torpedo tracks and altered course away. After dark, Sterlet attacked Brummer and three escorts returning from Oslo and when in a position north east of Kristiansand. She fired three torpedoes which were seen but one of them could not be avoided and hit and sank Brummer²¹. Sterlet was counter attacked by Falke and F5 who did not claim success but may well have sunk her²². Sterlet failed to return from patrol and it is possible that she was the victim of an attack by the German minesweeper M75 on 18th April after a night attack by a submarine on a convoy with two torpedoes. During a close depth charge attack a submarine broke surface and was sighted. It is also possible that she was mined as her return route took her through one of the German fields laid on 8th April. She was lost with all hands including her Commanding Officer, Lieutenant Commander GHS Haward RN, four other officers and 35 men. In the Heligoland Bight also on 15th April, Unity (Lieutenant JF Brown RN) fired three torpedoes in rough weather at a small U-boat at a range of 2000 yards on a broad track but missed.

Next day (16th April) Taku sighted the cruisers Glasgow and Sheffield off Andaisnes but she had been warned of their presence and there was no confusion. Triad off Oslo Fjord reported that the anti-submarine activity was now so intense that success was unlikely. She was ordered to withdraw to a position off Arendal. The large minelaying submarine Porpoise (Commander PQ Roberts RN) which had left Rosyth on 13th April to patrol off Egersund, encountered the small U-boat U3 and fired a full salvo of six torpedoes at her but missed. On 17th April, Taku still in the Trondheim area received a report of five German destroyers approaching her position. At 0335 she fired four torpedoes at a destroyer, which made a heavy counter attack with depth charges. Fortunately the torpedoes and the depth charges all missed for her adversary was the British Ashanti. Further south Seal (Lieutenant Commander RP Lonsdale RN) acted as a navigational beacon for the bombardment of Sola airfield near Stavanger by the heavy cruiser Suffolk. Triad, still in the Skagerrak, attacked the E-boat depot ship Tsingtau escorted by trawlers with four torpedoes. The range was 1500 yards and her firing position was good but she missed due to a drill failure when firing.

On 18th April, Seawolf (Lieutenant Commander JW Studholme RN), patrolling north of the Skaw, made a night attack on a convoy of three supply ships escorted by four trawlers. Although the range was long (4000 yards) she only fired two torpedoes but followed them up with four more. She obtained two hits sinking Hamm of 5874 tons. Two days later (24th April) Triad fired six torpedoes at a convoy of three ships at 2700 yards and claimed one or possibly two hits²³. Triad had now expended all her torpedoes and she was recalled to base. A few hours later Swordfish (Lieutenant PJ Cowell RN) fired a full salvo of six torpedoes at the same convoy (three ships with four escorts) but the range was long (5000 yards) and the submarine was swinging as she fired and all torpedoes missed²⁴. Finally on 21st April, the French submarine Orphee fired two torpedoes at a U-boat off the Dutch coast. She claimed a hit at the time but this is not supported by post war research.

In this critical week (15th - 21st April) when much depended on stopping reinforcements arriving to oppose our forces at Namsos and Andalsnes, our submarines attacked five convoys. They used twenty-seven torpedoes and sank an escort vessel and two supply ships totalling 10,274 tons. This did not check the flow across the Skagerrak to any degree; many convoys crossed without being sighted at all, and many troops were flown across in transport planes. However a U-boat was sunk and this was one out of five attacks on this type of target in which twenty torpedoes had been expended. Of the warships attacked, two minesweepers were sunk but Tsingtau was missed. Against these successes we lost Sterlet. It was not that the enemy had efficient antisubmarine detection devices. They had not, and their hydrophones, although an improvement on earlier types, were greatly inferior to active systems such as the British asdic. The problem was that the short nights only just gave time to re-charge the submarines' batteries. If the submarine was disturbed at night or forced to dive, she would probably face the second day without a full battery. Anti-submarine vessels therefore did not have to be able to detect submerged submarines. There just had to be plenty of them and they simply had to wait around and they could hunt our submarines to exhaustion²⁵.

The German Navy soon found that it was safer to cross the Skagerrak at night. After dark our submarines had to exert all their efforts to re-charge their batteries, and this could best be done by withdrawing from the convoy routes to quieter areas. They were therefore less likely to make contact at night and, in any case the submarines could seldom sight convoys as far away at night as they could in good visibility by day. To make matters worse, on 18th April and unknown to us, the four German minelayers reinforced by H.Danzig and Kaiser were occupied in laying anti-submarine minefields in the Kattegat. VA(S) called for help from the Home Fleet to attack the German antisubmarine vessels at night. A night sweep by four destroyers was planned for 17th/18th April but it had to be postponed. The C-in-C then cancelled the sweep, as he did not consider it 'to be an operation of war'. The operation of submarines in the eastern Skagerrak was, with the shorter nights, also fast ceasing to be an operation of war. A respite was earned when the French Navy came to VA(S)' aid. Three large 40-knot destroyers²⁶ made a sweep on the night of 23rd/24th April. They engaged the two patrol boats V702 and V709 and sank a trawler, but did not have time to penetrate into the eastern Skagerrak. They just missed the German minelayers Roland and Cobra on their way from Wilhelmshaven to Kristiansand. They were heavily attacked from the air as they returned, but fortunately escaped damage. The French destroyers Chevalier Paul, Milan and Tartu and the British Sikh and Tartar made a second sortie, which was unsuccessful, on 3rd/4th May. In between these destroyer raids, Roland and Cobra added an anti-submarine section to the Skagerrak minefield.

This field sank the Norwegian Kem of 1706 tons and the coaster V of 1400 tons and a third ship was damaged.

The brand new submarine Tetrarch (Lieutenant Commander RG Mills RN) left Rosyth on 13th April to patrol off Hallo (near Lillesand) and at 1830 on 23rd April she attacked a large transport or supply ship with an escort of three destroyers. She only fired two torpedoes at a range of 4000 yards, it was flat calm and the escort saw the torpedo tracks and the torpedoes were avoided. She was then subjected to a heavy counter attack and at 2222 fired two torpedoes at her tormentors but missed. The enemy renewed their efforts and she was held down not only all that night but all the next day too. In trying to shake the enemy off she lost control and on two occasions dived to 400 feet²⁸. She finally was able to shake off the enemy and surface after being submerged for forty-three hours. She had, fortunately, managed to surface for a few minutes in the middle to get a breath of fresh air.

On 22nd April, after her turn round of about a week, Trident (Lieutenant Commander GM Sladen RN) left Rosyth to patrol off the Naze. On 25th April she fired two salvoes of two torpedoes each at a southbound merchant ship in ballast. The range was 4500 yards and she missed with both. Truant (Lieutenant Commander HAV Haggard RN), after a little longer in harbour, left Rosyth on 24th April to land supplies, arms and explosives for the Norwegian Army in Sogne Fjord. Soon after she left harbour, she was damaged by an explosion and had to return. Whether this was a mine or the premature explosion of a U-boat's torpedo is not known. On 29th April Trident made a reconnaissance of Kors Fjord, which is the southern entrance to Bergen. It was by now clear that all the enemy traffic was using the inner leads behind the islands and that patrol outside in the open sea was unlikely to intercept it. Next day, therefore, she dived into the Selbjorn Fjord into the inner leads and spent the night charging in Bjorn Fjord. She patrolled the next day at periscope depth in the inner leads but nothing appeared until 0930 2nd May when Clare H Stinnes of 5000 tons was seen approaching from the south. Trident fired two torpedoes at 2500 yards but missed. She then surfaced and engaged with her gun. After firing 70 rounds, the enemy ship was forced to beach herself on Skorpa Island. Trident then fired another torpedo, which hit under the fore hold, after which she decided to regain the open sea without delay. She ran down Kors Fjord at full speed on the surface. She reached the entrance safely but then an aircraft appeared and she had to dive. Two patrol craft then came up and she was depth charged and hunted for some hours²⁹.

On 29th - 30th April, unseen by any of our submarines, four of the German surface minelayers laid mines in a new position. This was north of the Great Fisher Bank well to the west of the Skagerrak barrage and north of the German declared area. These mines were later to cause us grievous losses. Another submarine was lost at about this time by accident. On 29th April, Unity, soon after she had left Blyth for patrol, was run down by a Norwegian merchant ship in the war channel and sunk. Her Commanding Officer, Lieutenant FJ Brooks RN and most of her ships company were rescued, but one officer and three men were drowned.

On 4th May, Severn (Lieutenant Commander BW Taylor RN) south of Stavanger came upon the Swedish Monark of 1786 tons and stopped her. She was found to be in German hands and was sunk by a single torpedo after providing for the safety of the Swedish crew and capturing the Germans. On 6th May, Snapper (Lieutenant WDA King RN) patrolling inside the German declared area fired two torpedoes at 2000 yards at a zig-zagging supply ship which had air and surface escort. It is thought that the aircraft sighted the submarine just before firing as it was glassy calm and that the torpedoes were avoided. During this attack a destroyer approached from the opposite direction but took no notice and went straight on. On 8th May Taku in the Skudenes area, fired a full salvo of ten torpedoes at two transports escorted by two torpedo boats and two aircraft. The range was 2000 yards and she claimed hits on one transport and a torpedo boat. She, in fact, sank the torpedo boat Mowe but a hit on a transport has not been confirmed.

While our submarines were doing their best to cut the communications of the German forces in Norway, the French submarines of the Tenth Flotilla at Harwich were used to patrol west of the German declared area, off the Dutch coast and later on the south west coast of Norway. They made some seventeen patrols altogether in this period. On 22nd April, one of the larger French submarines, Sfax, was sent to patrol south west of Norway. She fired a total of five torpedoes in two salvoes at a convoy but the range was very long (7000 yards) and it is not surprising that she missed. On 9th May, Doris was sunk by U9 in the southern North Sea and on 11th Amazone missed a U-boat with two torpedoes fired at 1200 yards in the same area.

In the early days of May, the British forces in central Norway were evacuated from Andaisnes and Namsos. The German army then relieved Trondheim and pushed on up the road to the north. The whole of central and southern Norway was soon firmly in their hands. With this withdrawal, it was decided that the Norwegian submarine B6 should make for the United Kingdom. She was sent to Floro to fuel but partly because of the reluctance of her crew to leave their families in Norway and partly because of German threats to bomb the town unless she was surrendered, she was handed over to them on 18th May.

The attempt by the Royal Navy, especially its submarines, to prevent the invasion of Norway had failed. On 10th May, the Germans invaded the Netherlands and the whole maritime strategic situation was radically changed. Although operations continued for another month or so around Narvik, the Norwegian campaign as far as submarines were concerned had ended. It is time, therefore, to summarise the results. Altogether twenty-nine individual British and Allied submarines opposed the invasion of Norway³⁰. They made forty-seven torpedo attacks firing 166 torpedoes and laid five minefields totalling 232 moored contact mines. Twenty of the torpedo attacks succeeded, sinking the light cruiser Karlsruhe, the sloop Brummer, three minesweepers or patrol craft and severely damaging the pocket battleship Lutzow. They also sank thirteen ships of 66,527 tons and probably sank or damaged five more ships of 19,900 tons. Against this they lost five of their number: two to U-boat attack, one³¹ to the counter attacks of anti-submarine vessels, one by striking a mine and one by accident. It may seem that to succeed in only twenty out of forty-seven attacks needs comment, although in subsequent campaigns submarines did not always do as well. In five cases the torpedoes were fired at long range so that a hit would have been pure luck. In five cases the miss can be attributed to a drill or torpedo failure and in four cases too few torpedoes were fired in the salvo to ensure a hit. In four cases the enemy saw the torpedoes approaching or the splash of discharge and was able to take avoiding action. In one case the range was too short for the torpedoes to take up their depth, and in another the shot can only be described as a forlorn hope. In three cases insufficient information has survived to make an assessment and in only three cases is it inexplicable that a hit was not obtained. No single reason for the apparent lack of marksmanship can therefore be deduced. It is however relevant to note that practice in making torpedo attacks had ceased on the outbreak of war. There was a notion that practice was for peacetime, and that in war one learnt on the job. New submarines and submarines completing refit were granted a period to work up, but this was short and unorganised and was often cut short for operational reasons. No doubt if everything had been perfect more ships would have been sunk but not all that many more, and certainly not enough to alter the effect on the campaign.