'Tungsten' was a raid by the Royal Navy on the German battleship Tirpitz, and designed to damage or sink the ship at her base in the Kaafjord spur of the Altafjord in the far north of Norway before the warship could be rendered fully operational once more following a period of repairs (1/3 April 1944).

The British decision to attack was motivated by fears that the battleship, upon re-entering service, would attack strategically and diplomatically important 'Arctic convoys' carrying supplies to the USSR. Removing the threat represented by Tirpitz would also allow the Allies to redeploy the capital ships which up to this time had perforce to be held in the North Sea to counter any excursion by the German battleship. After four months of training and preparations, Admiral Sir Bruce Fraser’s Home Fleet sailed on 30 March 1944 and aircraft launched from five aircraft carriers struck the Kaafjord on 3 April. The raid achieved surprise, and the British aircraft met little opposition. Some 15 bombs hit Tirpitz, and strafing by fighter aircraft inflicted heavy casualties on her gun crews. Four British aircraft and nine airmen were lost during the operation.

The damage inflicted during the attack was not sufficient to sink or disable Tirpitz, however, but the German warship suffered considerable damage to her superstructure and unarmored areas, with 122 members of her crew killed and another 316 wounded. The German navy decided to repair the battleship, and the relevant work had been completed by the middle of July. The British conducted further carrier raids against Tirpitz between April and August 1944 in the hope of prolonging the period she was out of service, but none was successful.

The threat posed by Tirpitz had exercised an important effect on British naval strategy during World War II. The ship had been commissioned in February 1941 and completed her crew training later in the same year. At a similar time the German high command decided to station the battleship in Norway in a deployment intended to deter a feared Allied invasion of Norway and also to threaten the convoys which regularly sailed through the Arctic Sea to the USSR. These convoys carried large quantities of war matériel from ports in the UK and Iceland, and were frequently attacked by the Norway-based German air and naval units. Tirpitz arrived in Norway during January 1942 and operated from anchorages located in fjords whose twisting courses and mountain-flanked shores made air attack very difficult. While Tirpitz was operational, the Allies had no option but to maintain a powerful force of warships with the Home Fleet to guard against the possibility of a sortie against the Arctic convoys, and capital ships accompanied most convoys part of the way to the USSR.

The British attacked Tirpitz several times during 1942 and 1943. When the battleship sortied to intercept the PQ.12 convoy on 6 March 1942 in 'Nordmeer', the fleet carrier Victorious, which formed part of the convoy’s escort, attempted to attack her using torpedo bombers. These aircraft launched 20 torpedoes at the battleship, but all of them missed. On several occasions during 1942 and 1943 RAF and Soviet bombers tried to attack Tirpitz in her anchorages, but achieved no success. On 23 September 1943 in 'Source', two British 'X' class midget submarines succeeded in penetrating the defences around the battleship at her main anchorage in the Kaafjord and placed large explosive charges in the water beneath her. This attack caused extensive damage to Tirpitz, putting her out of service for six months.

Repairs to Tirpitz were carried out using improvised facilities in the Kaafjord as it was considered too risky to attempt to move the damaged warship to Germany. Instead, equipment and work crews were shipped to the fjord from German ports. On the night of 10/11 February 1944, 15 Soviet aircraft attacked the battleship but caused no damage. By 17 March, the repairs to Tirpitz's armament, machinery and hull had been completed, but several minor repair tasks remained. During the period the ship was under repair, Scharnhorst, the only remaining operational German capital ship, was sunk on 26 December during her 'Ostfront' sortie that led to the Battle of the North Cape. After this, the Royal Navy stopped deploying battleships to cover Arctic convoys. By this stage of the war the Allies also had large numbers of anti-submarine and anti-aircraft escort ships available, and were able to assign such vessels as strong forces to protect all of the Arctic convoys. U-boats operating in the Norwegian Sea were rarely able to evade the convoy escorts, and few merchant vessels suffered damage from German attack.

The British government and the Royal Navy were nonetheless still concerned about the threat posed by Tirpitz as and wen she re-entered service. Allied intelligence tracked the progress of work on the battleship using decrypted German radio signals, photo-reconnaissance flights and eyewitness reports from agents in Norway. It was feared that the battleship could sortie and attack convoys in the Norwegian Sea or Atlantic Ocean after the repair work had been completed. The need to guard against this possibility would also occupy warships needed to support the planned 'Neptune' (iii) landings in France at the start of 'Overlord', and it was therefore decided late in 1943 to make further attempts to sink the battleship.

Despite Allied concerns, Tirpitz in actuality posed only a limited danger to Allied shipping. From a time late in 1943, the battleship was unable to put to sea for crew training as of a result of German fears of Allied attack, and an increasingly acute shortage of fuel. The shortage also meant that the Germans were unable to move the battleship between anchorages to make her more difficult to locate and attack.

The options for attacking Tirpitz in the Kaafjord were limited. Another attack using submarines was considered impractical as intelligence gathered from intercepted radio traffic and agents indicated that the battleship’s underwater defences had been improved and more aerial reconnaissance patrols of the region were being flown. The commander of RAF Bomber Command, Air Chief Marshal Sir Arthur Harris, also refused to attempt a heavy bomber raid on Tirpitz on the grounds that the Kaafjord area lay outside the effective range of these aircraft and that the battleship’s and shore batteries' Flak defences would cause heavy casualties. After these two options had been removed from consideration, the task was assigned to the Home Fleet’s aircraft carrier force which at this time comprised the large fleet carriers Furious and Victorious and four smaller escort carriers.

Planning for the raid on Kaafjord began in December 1943. Admiral Sir Bruce Fraser, the commander of the Home Fleet since 8 May 1943, was not optimistic about the prospects for success, and had to be persuaded to undertake the operation by the First Sea Lord, Admiral Sir Andrew Cunningham. Fraser gave his second in command, Vice Admiral Sir Henry Moore, responsibility for the planning and execution of the raid. The operation was initially designated 'Thrustful' but was later renamed 'Tungsten'. The attack was originally scheduled for mid-March 1944, shortly before the time Allied intelligence believed Tirpitz would become operational. However, the undertaking was delayed by two weeks while Victorious was outfitted with new radar equipment. The British considered cancelling 'Tungsten' in February as Victorious was also needed in the Indian Ocean to counter a build-up of Japanese warships at Singapore. To enable the attack to proceed, the US Navy agreed to the temporary transfer of the fleet carrier Saratoga to the Eastern Fleet so that Victorious could be retained in the North Sea.

The plan for the raid was based on two dive-bombing attacks by Fairey Barracuda aircraft of the Fleet Air Arm. Each of the attacks was to involve 21 Barracuda warplanes escorted by 40 fighters: Vought Corsair fighters flying from Victorious were to provide protection against German aircraft while Grumman Wildcat and Grumman Hellcat fighters operating from Furious and the escort carriers Emperor, Pursuer and Searcher were to strafe Flak batteries on shore near Tirpitz, as well as the battleship herself. Further aircraft flying from Furious and the escort carrier Fencer were to protect the fleet against attack by German aircraft and/or U-boats. While British carrierborne aircraft had previously lacked a bomb capable of penetrating a battleship’s thick deck armour, it was hoped that the recently developed 1,600-lb (726-kg) armour-piercing bomb would be able to pierce at least the first layer of Tirpitz's armour if they were dropped from an altitude of 3,500 ft (1065 m) or greater. The damage caused by such hits was expected to put the battleship out of service. Nine of the Barracuda warplanes were each to be armed with a single 1,600-lb (726-kg) bomb and a further 22 were each to carry three 500-lb (227-kg) semi-armour-piercing bombs that were capable of penetrating the lightly protected upper decks of the ship if dropped from an altitude of 2,000 ft (610 m) or greater. The remaining 10 aircraft were to be armed with 500- and 600-lb (227- and 272-kg) general-purpose bombs and with anti-submarine bombs intended to inflict casualties among the battleship’s crew and cause underwater damage if they exploded in the water near her hull. The aircraft carrying high-explosive bombs were to initiate the dive-bombing of Tirpitz as it was hoped that the detonations of these weapons would destroy at least some of the battleship’s Flak guns before the start of the main attack.

The FAA squadrons selected for 'Tungsten' undertook a programme of intensive training from February 1944. A high proportion of the crews were inexperienced, and the captain of Victorious estimated that 85% of the aircrew embarked on his ship had not previously operated at sea. The training programme was centred on Loch Eriboll in north-western Scotland which, like the Kaafjord, is surrounded by steep hills. Flying from the naval air station at Hatston in the Orkney islands group, the aircrew practised manoeuvring around this terrain to familiarise themselves with the tactics needed to avoid German Flak guns and deliver a successful attack on Tirpitz. The Royal Navy drew on intelligence about the defences of the Kaafjord to make the exercise range as similar to the conditions around Tirpitz as was possible, and the aircrew were extensively briefed on the locations of German positions. An area the size and shape of the German battleship was also marked on an island in the loch and repeatedly bombed.

The Allies meanwhile continued to monitor Tirpitz. Late in February the escort carrier Chaser transported photo analysts and the ground crews for an RAF photo-reconnaissance detachment to Vaenga airfield in northern Russia. These personnel were joined by three Supermarine Spitfire photo-reconnaissance aircraft and one Consolidated Catalina flying boat in March. The Spitfire aircraft flew regular sorties over the Kaafjord and took very detailed photographs of Tirpitz and the nearby Flak batteries on 12 and 13 March. After the photographs had been developed, the Catalina flew these images to the UK. Although the German forces in northern Norway detected the Spitfire flights, the Kaafjord area’s defences were not increased or placed on alert. On 16 March eight British, Free Dutch and Free Norwegian submarines assumed positions off the Norwegian coast after decrypted German radio traffic indicated that Tirpitz might have been preparing to depart the Kaafjord for Germany in order for her repairs to be completed. A further eight British and Free Dutch submarines were despatched on 18 March, but two days later it was concluded that Tirpitz was not about to put to sea and the submarines were diverted to other tasks or ordered back to port. On 21 March British intelligence warned the Admiralty that due to recent Soviet advances on the Eastern Front, the Germans were placing a strong emphasis on disrupting the flow of supplies to the USSR and could despatch Tirpitz to attack any convoys not escorted by capital ships. In response, Fraser was directed to provide battleship protection for the next Arctic convoy.

The final decision to launch 'Tungsten' was taken in the middle of March on the basis of a decrypted radio message that indicated that Tirpitz was almost ready for combat and would undertake high-speed trials on 1 April. As a result of the delays to the operation, the sailing of the attack force coincided with the departure of the JW.58 convoy to the USSR, and it was hoped that if German forces spotted the British fleet it would be assumed that the warships were supporting the convoy. As part of the final preparations for the attack, a full-scale rehearsal was undertaken over Loch Eriboll on 28 March. From 1 April the Admiralty received hourly weather reports from a group of Norwegian agents of the Secret Intelligence Service in Alta, near the Kaafjord.

The Royal Navy assembled a powerful force for 'Tungsten'. The main attack force comprised two wings of Barracuda dive-bombers: No. 8 Wing, comprising Nos 827 and 830 Squadrons, and No. 52 Wing, comprising Nos 829 and 831 Squadrons. While No. 8 Wing was normally based on Furious and No. 52 Wing on Victorious, Moore chose to station a squadron from each of the wings on each carrier so they could be launched simultaneously and go into battle as formed units.

The large number of warships assigned to 'Tungsten' were initially divided into two groups. Force 1 was personally commanded by Fraser on board the battleship Duke of York, and also included Victorious, the battleship Anson (with Moore and his staff on board), a light cruiser and five destroyers. Force 2 was commanded by Rear Admiral Arthur La Touche Bisset and comprised Furious, the four escort carriers, five destroyers and two tankers. It was planned that Force 1 would initially provide support for the JW.58 convoy and Force 2 would sail separately and proceed directly to a point off Norway where it would be joined by Anson and Victorious on 3 April to launch the raid during the following day.

Tirpitz's anchorage in the Kaafjord was protected by Flak batteries and fighter aircraft. At the time of 'Tungsten', four batteries of heavy Flak guns and seven batteries of light Flak guns were located on shore near the battleship. Several Flak vessels and destroyers were also generally moored near Tirpitz. The battleship herself was armed with 68 Flak guns. Equipment capable of generating an artificial smokescreen to hide Tirpitz from aircraft had also been installed around the Kaafjord. The Luftwaffe had only a small number of fighters stationed at bases near the Kaafjord, and their operations were constrained by a lack of fuel. British intelligence believed that the German fighter force in the area could be enlarged rapidly in the event of an emergency. The Luftwaffe typically conducted three reconnaissance flights into the Arctic Sea each day.

Force 1 departed the Home Fleet’s base at Scapa Flow in the Orkney islands group on 30 March, three days after the JW.58 convoy had sailed from Loch Ewe in north-western Scotland. Force 2 departed separately later in the same day. The convoy comprised 49 merchant ships escorted by a powerful force of 33 warships, including two escort carriers. German reconnaissance aircraft located the JW.58 convoy on 30 March, and all of the U-boats in the Norwegian Sea were directed to intercept it. German aircraft did not conduct wider-ranging sorties in search of the convoy’s battleship covering force or other Allied ships. A total of 17 U-boats attacked the JW.58 convoy between 1 and 3 April without success: none of the Allied ships suffered any damage, and the escorts sank four U-boats and shot down six German aircraft during the convoy’s voyage from Scotland to the USSR. The convoy reached its destination in the Kola inlet on 6 April. While several Allied aircraft had been lost during the voyage, most of them as a result of flying accidents, all of the ships arrived unscathed.

As a result of a combination of favourable factors, Fraser decided on 1 April to bring the raid on the Kaafjord forward by 24 hours. Decrypted German signals indicated that Tirpitz's trials had been delayed until 3 April, and Fraser hoped that an attack on this date would catch the battleship away from her usual, and therefore well-protected, mooring. Moreover, as the JW.58 convoy’s escorts were performing well and there was no indication that Tirpitz was about to sortie into the open sea, Fraser judged that Force 1 no longer needed to provide support for the merchant vessels. Weather conditions were also unusually good for the Norwegian Sea early in the spring, and were well suited to flying operations. After the decision to attack had been made, both tankers and two escorting destroyers detached from Force 2 and proceeded to a point 300 miles (485 km) to the north-west of Kaafjord, where they remained to supply any destroyers which ran short of fuel. The rest of Force 2 altered course to rendezvous with Force 1, and this was achieved at 16.20 on 2 April. After the two forces met, Duke of York, with Fraser on board, and two destroyers steamed to the north-west and took up a position where they would be able to intercept Tirpitz in the event that she had departed the Kaafjord without being detected. The remainder of the Home Fleet proceeded to the attack’s planned launch position.

The attack began during the early hours of 3 April. All the crews were woken shortly after 00.00 and underwent their final briefing from 01.15. The aircraft to be used in the attack were armed at this time. The crews began to board their aircraft at 04.00, and the aircraft started to take-off some 15 minutes later. At this time the warships were 120 miles (190 km) from the Kaafjord. Ten Corsair fighters drawn from Nos 1834 and 1836 Squadrons were the first aircraft to be launched, and were followed by the 21 Barracuda dive-bombers of No. 8 Wing: No. 827 Squadron was launched from Victorious and No. 830 Squadron rose from Furious. Seven of the Barracuda aircraft were each armed with one 1,600-lb (726-kg) bomb, and the others carried several 500- or 600-lb (227- or 272-kg) weapons. Once the Barracuda aircraft were airborne, the remaining escort fighters (30 Wildcat and Hellcat machines of Nos 800, 881 and 882 Squadrons) were launched. All the aircraft of the first wave were despatched successfully, and the force had come into formation by 04.37. Flying conditions remained excellent, and the Germans had not detected the British fleet during its approach.

The first wave headed for Norway at just 50 ft (15 m) above the sea to avoid detection by German radar. The aircraft began to climb to a higher altitude when they reached a point 20 miles (32 km) from the coast, and had reached 7,000 ft (2135 m) by the time they made landfall at 05.08. The force approached the Altafjord from the west, passing over the western end of the Langfjord before turning to the south and then looping to the north and attacking the battleship over the hills on the southern shore of the Kaafjord shortly before 05.30.

The arrival of the British force caught Tirpitz's crew by total surprise. While the aircraft had first been detected by a German radar station shortly after they crossed the Norwegian coast, the battleship was not immediately warned. At the time of the attack, Tirpitz was preparing to depart for her high-speed trials, and her crew were busy unmooring the vessel, and her five protective destroyers had already departed for the trials area in Stjern Sound. The warning from the radar station arrived shortly before the British aircraft appeared over the Kaafjord, and the battleship’s crew were still in the process of moving to their battle stations as the attack started. At this time not all of the watertight doors had been closed and some damage-control stations were not fully manned.

As planned, the British raid began with Hellcat and Wildcat fighters strafing Tirpitz's Flak guns and the Flak batteries located on the shore. The attack inflicted heavy casualties on the battleship’s gunners, disabled her main Flak control centre and damaged several guns. The fighters also strafed several Flak ships in the Kaafjord. The 21 Barracuda dive-bombers began their attack shortly after this, and within 90 seconds had struck Tirpitz with one general-purpose bomb, three 500-lb (227-kg) semi-armour-piercing bombs and three 1,600-lb (726-kg) bombs. In overall terms, 10 bombs struck the battleship during the first attack: most of these bombs did not penetrate the ship’s armoured deck as they had been dropped from too low an altitude. Hundreds of crew men were killed or wounded, and the commanding officer, Kapitän Hans Meyer, was among the latter. The ship’s intelligence officer assumed command. The battleship also drifted into the western shore of the Kaafjord and ran aground, but was quickly refloated. One of No. 830 Squadron’s Barracuda aircraft crashed following the attack with the loss of all three members of its crew. The surviving aircraft of the first wave began landing back on the carriers at 06.19, and all had been recovered by 06.42.

The first of the second wave’s aircraft departed at 05.25. One of No. 829 Squadron’s Barracuda aircraft crashed shortly after take-off, and another aeroplane from this squadron was not launched as a result of engine problems. Only two of the Barracuda aircraft in this wave were armed with 1,600-lb (726-kg) bombs. As with the first attack, 40 fighters accompanied the dive-bombers: these fighters were 10 Corsair machines of Nos 1834 and 1836 Squadrons, all of the 20 Wildcat machines assigned to Nos 896 and 898 Squadrons and 10 Hellcat machines of No. 804 Squadron. All of the aircraft had been launched by 05.37, and the force had an uneventful flight to the Kaafjord area. While the German defences were now alert, the artificial smoke screen being generated around the Kaafjord was not yet sufficient to hide Tirpitz.

The second attack was similar to the first. It began with Hellcat fighters strafing the anti-aircraft batteries while Wildcat fighters attacked the battleship. The fighters also attacked German ships in the Kaafjord and a radio or radio direction-finding station. The Barracuda dive-bombers executed their attack at 06.36 and struck Tirpitz with one 1,600-lb (726-kg) and four 500-lb (227-kg) bombs within a minute. The German defences in the Kaafjord had received little warning of the incoming raid, and as the growing smokescreen hid the British aircraft the Flak gunners had to fire blindly and shot down only one of the Barracuda aircraft. The Aircraft of the second wave landed back on the carriers between 07.20 and 07.58. A damaged Hellcat had to ditch near the Canadian destroyer Algonquin and one of the Corsair aircraft suffered heavy damage as a result of a landing accident.

During the period in which the air attacks were delivered, a force of 25 Wildcat and Supermarine Seafire fighters from Nos 801, 842 and 880 Squadrons provided air defence for the ships of the Home Fleet. Nine Fairey Swordfish torpedo bombers, which were also operated by No. 842 Squadron, undertook anti-submarine patrols. No threat to the fleet developed, however, and Corsair fighters took over the air-defence role at the end of the two attacks.

Nine Royal Navy airmen died during the raid.

Early in the afternoon of 3 April, Moore considered another raid on the Kaafjord during the following day, but decided against this as the preliminary assessment of photos taken during the attack had concluded that Tirpitz had been badly damaged. Moore was also aware that his aircrews were tired, and was reluctant to expose them to what would now be alert defences. He therefore ordered the fleet to return to base, and it reached Scapa Flow in the afternoon of 6 April. While King George VI and Prime Minister Winston Churchill sent congratulatory messages to the fleet, both Churchill and Cunningham remained highly concerned that Tirpitz could be returned to service. Cunningham also regretted Moore’s decision not to launch another attack on 4 April.

The two attacks on Tirpitz had proceeded largely to plan. The airmen found the defences and geography of the Kaafjord to be very similar to the Loch Eriboll training range, and one of the post-attack reports stated that the operation had been 'almost an exercise which [the aircrew] had frequently carried out before'. The most significant discrepancy between the operation’s plan and its execution was that many pilots dropped their bombs from an altitude below the specified minimum of 3,000 ft (910 m) in an attempt to improve their chances of hitting Tirpitz, and the bombs' reduced flight times may have meant that some of those which struck the battleship lacked the necessary velocity to penetrate her deck armour.

While two bombs that exploded in the water near Tirpitz opened holes in her hull and caused flooding, none of the 15 bombs that struck the battleship penetrated her main deck armour. As a result, her guns, magazines and machinery suffered no serious damage. Most of the damage was inflicted on the battleship’s superstructure and between her armoured decks. The starboard aircraft catapult and crane were destroyed, as were both of Tirpitz's Arado floatplanes. The no. two starboard 150-mm (5.91-in) gun turret was knocked out, and the no. three port 150-mm (5.91-in) turret suffered major damage. The officers' mess and several galleys were wrecked, and the ship was filled with smoke. Tirpitz's funnel was also struck by bomb fragments that badly damaged all of the boiler intakes. While the starboard turbine was knocked out by shock damage and two of the boilers were disabled after being contaminated by salt water used for firefighting, the battleship was still capable of steaming within the Kaafjord. Tirpitz's crew suffered heavy casualties: in overall terms, 122 men were killed and 316 were wounded, constituting some 15% of the battleship’s crew. Many of the casualties were Flak gunners who were killed or wounded by machine-gun fire from the British fighters.

The British fighters also damaged four patrol craft and one large repair ship: the captain of an armed trawler died and 13 other sailors on board these vessels suffered wounds. A few hours after the attack, Torstein Raaby of the Secret Intelligence Service group in Alta reported that there had been no civilian casualties, and that the local population was 'extremely impressed by the bombing'. Another report six days after the operation passed on the information that the Germans estimated that it would take months to repair the damage inflicted on Tirpitz

The commander-in-chief of the Kriegsmarine, Grossadmiral Karl Dönitz, directed that the damage inflicted on Tirpitz in 'Tungsten' be repaired. Although the battleship was no longer capable of operating against Allied convoys for lack of air support, it was considered desirable to retain her in service in order to tie down Allied naval resources. Repair work began early in May after a destroyer had delivered workmen and their equipment to the Kaafjord from Germany, and Tirpitz was able to steam under her own power by 2 June. She was capable of undertaking gunnery practice by the end of June, and all repairs had been completed by the middle of July. During this period the battleship’s Flak armament was augmented by the addition of more 20-mm cannon, modifying the 150-mm (5.91-in) guns so they could be used in the anti-aircraft role, and supplying anti-aircraft shells for the 380-mm (15-in) main guns. The defences of the Kaafjord were also strengthened during this period. Additional radar stations and observation posts were established, and the number of smoke generators located around Tirpitz was increased.

After 'Tungsten', British intelligence assessed that Tirpitz would be repaired within six months. Accordingly, on 13 April Cunningham directed Fraser to launch another attack on the battleship. While Cunningham believed that the Barracuda was incapable of carrying any weapon capable of sinking Tirpitz, he hoped that more air attacks would increase the period the battleship was out of service and adversely affect her crew’s morale. Fraser initially resisted Cunningham’s order, arguing that the prospects for a successful raid were poor as the Germans would have reinforced the defences around Tirpitz and weather conditions were likely to be worse than those encountered during 'Tungsten', but eventually agreed and Moore departed Scapa Flow on 21 April to deliver another attack on the Kaafjord. This 'Planet' raid was called off on 24 April as the weather over the target area was bad. Two other attacks,'Brawn' and 'Tiger Claw', also had to be cancelled on 15 and 28 May respectively because of adverse weather. Additional carrier raids were attempted in July and August after Allied intelligence determined that the repairs to Tirpitz were nearing completion. In 'Mascot' a force of 42 Barracuda dive-bombers and 40 fighters attacked Tirpitz on 17 July, but scored no hits as the battleship was hidden by a smokescreen. A further four carrier raids were conducted against the Kaafjord between 22 and 29 August as 'Goodwood' (ii), but these caused only light damage to the battleship.

Late in August the British came to the conclusion that further Fleet Air Arm attacks should not be attempted as the Germans were now able to cover Tirpitz in smoke before any Barracuda force could reach the battleship, and as the Barracuda could carry no bomb large enough to inflict heavy damage. As the destruction of Tirpitz was still seen as a desirable objective, the task was assigned to Air Chief Marshal Sir Arthur Harris’s Bomber Command. On 15 September a force of heavy bombers attacked the Kaafjord after refuelling at bases in northern Russia and inflicted irreparable damage on the battleship. Following this, Tirpitz sailed to an anchorage near Tromsø to be used as an immobile coast-defence battery. Another heavy bomber attack on 29 October caused only minor damage, and a third raid was mounted on 12 November as 'Catechism', in which Tirpitz was struck by several 12,000-lb (5443-kg) Tallboy bombs and capsized with heavy loss of life among her crew.