[5] After the German invasion of the Soviet Union on 22 June 1941 the Allies began sending convoys loaded with supplies through the Norwegian Sea and Arctic Ocean to ports in northern Russia.

The Arctic convoys that were dispatched during 1941 and early 1942 were lightly opposed, with only a single Allied merchant ship and the destroyer HMS Matabele being sunk by German submarines prior to March 1942.

[6][7] Harsh weather conditions, including extreme cold, heavy seas and gales, made air and naval operations in the area difficult for all of the combatants.

[5] The Allies learned of Tirpitz's arrival at Trondheim on 17 January from Ultra intelligence obtained by decrypting intercepted German radio signals.

[15] He cancelled the raid on Tromsø after the Admiralty passed on intelligence that another group of German ships was being transferred to Trondheim; these were the heavy cruisers Admiral Scheer and Prinz Eugen with three destroyers.

While the failure to prevent the battleships from passing through the English Channel was embarrassing to the British, the German move ended the threat which the warships at Brest had posed to Allied shipping in the Atlantic.

[21] Due to the presence of the battle group at Trondheim, the Home Fleet was directed to provide a powerful distant covering force for the next Arctic convoys; this was the first time that this had been done.

PQ 12 left Iceland bound for the Soviet Union, and QP 8 departed Murmansk in northern Russia to return ships to the Atlantic.

[24] Tovey had requested that the convoys sail simultaneously to make it easier for the Home Fleet to protect them while they passed through the waters between Jan Mayen and Bear Islands where they would be at greatest risk of attack by German surface ships.

[20] Retaining part of the fleet at Scapa Flow would also help to keep ships and their crews ready over what was anticipated to be a lengthy campaign, with Tovey believing that Gneisenau and Scharnhorst would join Tirpitz over the summer after they were repaired.

[27][28] The Admiralty disagreed with this analysis and ordered Tovey to put to sea on 3 March so that the full force of the Home Fleet could be brought to bear against Tirpitz if she sailed.

[28] The crew of a German Focke-Wulf Fw 200 Condor maritime patrol aircraft sighted ships of PQ 12 near Jan Mayen at around noon on 5 March.

The commander of the German Naval Group North, General Admiral Rolf Carls, requested permission to attack the convoy using Ciliax's force.

Contact was first made by the submarine HMS Seawolf at 6:01 pm on 6 March, with its crew spotting a single large warship while patrolling north of the exit to Trondheim Fjord.

[38][44] The German battle group sailed north-east along the coast of Norway at 23 knots (43 km/h; 26 mph) for the remainder of 6 March and turned north at midnight.

Friedrich Ihn attacked and hit Izhora with a torpedo, but the cargo ship's radio operator managed to send a sighting report before it sank.

Radio direction finding indicated that this transmission had been sent from near PQ 12, and Tovey issued orders for six of his destroyers to detach and search the route that the German ships might be using to return to Norway from Izhora's position while the main battle fleet proceeded to the north-east to protect the convoy.

[52][53] Another radio signal from a German submarine that was intercepted at 7:40 pm led Tovey and his staff to wrongly believe that Tirpitz was rapidly sailing south.

The battleship then turned to the south-west on a course which Ciliax believed would intercept the convoy and her crew were called to action stations ahead of the expected battle.

[59][60][61] Naval Group North sent Ciliax a signal at 6:20 pm that suggested that PQ 12 might have abandoned its voyage after being spotted on 5 March and gave him permission to break off the operation if he wished.

It was taking only two or three hours at this time for intercepted German naval radio signals to be decoded, which allowed the forces at sea to rapidly respond to this intelligence.

[58] After changing course, Tovey broke radio silence to report to the Admiralty that he was heading north with the main body of the fleet and lacked protection against submarines.

He also requested that the Admiralty assume direct control of the Home Fleet's separate forces of cruisers and destroyers given that it had a better understanding of their locations and could more easily communicate with them.

[63] Tovey was hopeful that the Germans would intercept his radio signal and recall Tirpitz as this would guarantee the safety of PQ 12 and possibly bring the battleship within range of Victorious's aircraft.

[35] Tovey received further Ultra intelligence during the early hours of the morning that confirmed the Germans were returning to Trondheim and provided Tirpitz's expected position at 1 pm that day.

[75] In his report, Bovell criticised Lucas for beginning the attack before his aircraft were in the proper position and judged that the other pilots had released their torpedoes at too great a distance from the battleship.

[76][77] Tovey did not attempt a second torpedo bomber attack on Tirpitz as Victorious's aircraft were unable to operate in the defended airspace around Narvik with any prospect of success.

[78] On 9 March HMS Shera, one of two armed Norwegian whalers that had been dispatched from Iceland to strengthen PQ 12's escort, capsized while searching for the convoy.

[88] Operation Sportpalast also demonstrated the threat which the German warships in Norway posed to the Arctic convoys, and it was also decided that the Home Fleet would cover them all in the future.

The Fleet Air Arm inflicted further damage during Operation Tungsten on 3 April 1944, but several later carrier attacks failed due to bad weather and the shortcomings of British naval aircraft.