The aircraft departed from bases in northern Scotland and, due to clear weather conditions, the Commonwealth airmen were able to accurately target and bomb the battleship.

Stationed in fjords on the Norwegian coast, the battleship was capable of overwhelming the close-escort forces assigned to the Arctic convoys or breaking out into the North Atlantic.

[1] To counter this threat, the Allies needed to keep a powerful force of warships with the British Home Fleet, and capital ships accompanied most convoys part of the way to the Soviet Union.

During Operation Source on 22 September, she was severely damaged by explosives placed on her hull by Royal Navy personnel who had used midget submarines to penetrate Kaafjord.

[8] As Tirpitz could not be repaired and Soviet forces were advancing towards Kaafjord, Grand Admiral Karl Dönitz, the commander of the Kriegsmarine (the German Navy), ordered that she be transferred to near the northern Norwegian city of Tromsø and used as an immobile battery to defend the area from attack.

To extend their range, the Lancasters were fitted with extra fuel tanks and more powerful engines, and their forward and mid-upper gun turrets and pilot's armour plate were removed.

[25][26] A report issued by the Royal Navy's Naval Intelligence Division on 3 November judged that it remained necessary to attack Tirpitz in northern Norway.

[27] Two de Havilland Mosquito meteorological aircraft were stationed at RAF Sumburgh from 4 November, from where they conducted daily sorties to monitor weather conditions in the Tromsø area.

One of the Mosquito meteorological aircraft flew over the area that evening, and its crew reported encountering patches of cloud when they returned to Scotland shortly after midnight on the night of 11–12 November.

5 Group, Air Commodore Ralph Cochrane, decided to attempt another attack in the hope that the bombers would encounter clear weather over Tromsø.

As had been the case during Operation Obviate, they crossed the Norwegian coast between the towns of Mosjøen and Namsos where a gap in German radar coverage had been located.

Tait spotted Tirpitz from 20 miles (32 km) away, and later recalled that she was "lying squat and black among her torpedo nets like a spider in her web, silhouetted against the glittering blue and green waters of the fjord".

[62] Many sailors manning Tirpitz's anti-aircraft guns were killed or wounded by the bombs, resulting in a significant reduction in the volume of fire directed at the Lancasters.

[69] Cutting continued for two further days, and was finally abandoned when it was assessed that the oxygen supply inside the wreck would have been exhausted; no survivors were recovered during this period.

The corpses which were recovered from the wreck by scrappers were initially buried alongside unwanted parts of Tirpitz, but this ceased following complaints by a local church minister.

[81] The Air Ministry issued a communique announcing Tirpitz's destruction on 13 November, leading to celebratory stories in many British newspapers the next day.

The citation recognised his "conspicuous bravery and extreme devotion to duty in the face of the enemy, constantly exemplified over a long period of operational flying" and role in leading three attacks on Tirpitz.

[75] In addition to the heavy loss of life, the destruction of the battleship left the Kriegsmarine without any of the capital ships needed to threaten Allied convoy routes.

[94] Sweetman judged that the failure ultimately resulted from the order to intercept the bombers being issued too late, and a lack of clear plans to coordinate the defence.

For instance, German naval personnel could not pass information directly to their Luftwaffe equivalents, as messages had to be sent through single-service channels and could only be transmitted between services at relatively senior levels.

[90] The historian Daniel Knowles reached a similar conclusion, labelling Tirpitz's defences "chaotic" due to the poor communications between the battleship and Bardufoss.

Angus Konstam has written that the battleship posed no threat to Allied shipping from April 1944 due to the damage inflicted in Operations Source and Tungsten.

He argued that the subsequent attacks were motivated by Churchill and other members of the War Cabinet having an "obsession" with destroying Tirpitz, and that Operations Obviate and Catechism were mainly undertaken for propaganda purposes.

[101] Patrick Bishop has observed that "the zeal of the pursuit, whipped on by Churchill, seems excessive now, but wartime created its own dynamic", and that Operation Catechism contributed little towards ending the war.

[84] Similarly, Niklas Zetterling and Michael Tamelander have judged that although "the British were not fully aware that the Germans had written off Tirpitz as an offensive weapon in autumn 1944, their final efforts appear almost overzealous".

[102] The official history of British intelligence in World War II states that Dönitz's use of the battleship to tie down Allied resources was successful, and "in her last days she briefly excelled" in this role.

[104] John Ellis reached a similar conclusion, and also argued that Operations Obviate and Catechism were justified as they contributed to sustaining the Fortitude North deception campaign that had led the Germans to maintain powerful ground forces in Norway in the mistaken belief that the Allies were planning amphibious landings there.

[105] The retired United States Navy Rear Admiral William H. Langenberg judged that "because of her strategic importance, all the Allied attempts to disable or sink Tirpitz were justified".

Konstam noted that Operations Paravane, Obviate and Catechism were "well-planned and conducted" and "provided a neat ending to what had been a long and often tortuous aerial campaign".

[108] Jan Forsgren observed that the lack of attention given to the battleship's defence by the German high command was "quite remarkable" in light of the previous British attacks.