'Catechism' was the British sinking of the German battleship Tirpitz by bombing attack (12 November 1944).
The mere existence of this German capital ship in Norwegian waters had been a major operational impediment to the activities of the Home Fleet over a considerable period, and a constant threat to the Allied convoys transporting war supplies to the Soviet ports of Murmansk and Arkhangyel’sk via the Arctic convoy route round the North Cape.
While in northern Norwegian waters Tirpitz had been attacked on 16 occasions (six times by RAF bombers and the other 10 times by Fleet Air Arm attack aircraft) in the period between 28 January 1942 and 29 October 1944. By October 1944 the German battleship had been moved some 200 miles (320 km) south from the Altafjord, and now lay in the bay of Håkøybotn within the Tromsøfjord, about 3 miles (4.8 km) to the west of the city of Tromsø.
On 29 October a force of 38 Avro Lancaster heavy bombers, operating from a Soviet base and each carrying one 12,000-lb (5443-kg) 'Tallboy' penetration bomb, set off in 'Obviate' to attack Tirpitz, which was damaged at the stern by a near miss, which was the best the RAF bombers could manage in adverse bombing conditions of patchy cloud.
Air Chief Marshal Sir Arthur Harris, commanding RAF Bomber Command, decided that another raid was in order, and 'Catechism' was launched as soon as the weather permitted, on 12 November, by 32 Lancaster bombers of Nos 9 and 617 Squadrons, each bomber armed with a single 'Tallboy' bomb, under the command of Group Captain J. B. Tait. Poor liaison meant that German fighter cover from Bardufoss did not appear, and the Lancaster bombers were able to bomb without hindrance.
As in earlier attacks, the ship used her 14.96-in (380-mm) main guns to fire fragmentation shells against the bombers, which approached the battleship at 09.35, and this fire forced the bombers to disperse temporarily, but did not break up the attack. The Lancaster bombers then dropped 29 'Tallboy' bombs on the ship, scoring two direct hits and one near miss. Several other of the bombs landed within the anti-torpedo net barrier and caused significant cratering of the seabed, which removed much of the sandbank that had been constructed to prevent the ship from capsizing.
One bomb penetrated the ship’s deck between A and B turrets but failed to explode. A second bomb hit amidships between the aircraft catapult and the funnel, and caused severe damage. A very large hole was blown into the ship’s side and bottom and the entire section of belt armour abreast of the bomb hit was completely destroyed. A third bomb may have struck the ship a glancing blow on the port side of C turret but been deflected by the turret armour.
Another three bombs detonated under the water close alongside the battleship and caused more damage.
The amidships hit and subsequent detonation caused major flooding, which quickly increased the port list from the 1° figure resulting from an earlier attack to between 15° and 20° and, after 10 minutes, to 30° to 40°. Kapitän Robert Weber then issued the order to abandon ship. Progressive flooding increased the list to 60° by 09.50, though the angle of list then appeared to have been stabilised, if only temporarily. Eight minutes later, however, a large explosion rocked C turret, the turret roof and part of the rotating structure being hurled some 80 ft (25 m) into the air and across into a group of men swimming to shore, crushing them. Tirpitz then rapidly capsized and rolled over, burying her superstructure in the sea floor.
In the aftermath of the attack, rescue operations attempted to reach men trapped in the hull. Workers finally managed to rescue 82 men by cutting through the bottom hull plates. The figure for the death toll vary from some 950 to 1,204 out of a crew of 1,900 men. Approximately 200 survivors were transferred to the heavy cruiser Lützow in January 1945.
The wreck remained where it was until after the war, when a joint German and Norwegian company began salvage operations. These lasted from 1948 to 1957.
Major Heinrich Ehrler was in command of 9./Jagdgeschwader 5 based on Bardufoss airfield with 12 Focke-Wulf Fw 190A-3 fighters. The Staffel was at 10-minute readiness status as a result of the continuing pressure of British bombers in the Tromsø area. Ehrler’s unit was scrambled into the air, but he received conflicting messages about the location and course of the British aircraft. Some reports claimed that Alta was the target area, others indicated Bodø. When it finally became clear that the target was the Tirpitz, it was too late for the fighters to intercept.
The performance of the Luftwaffe in the defence of Tirpitz was highly criticised after the battleship’s loss. Ehrler was blamed for the Luftwaffe’s failure to intercept the British bombers, and was later court-martialled in Oslo and threatened with the death penalty. Evidence was shown that his unit had failed to help the Kriegsmarine when requested. He was sentenced to three years in prison, but released after a month, demoted, and reassigned to a Messerschmitt Me 262 jet fighter squadron in Germany.
Ehrler was exonerated by further investigations, which decided that the reason for the Luftwaffe’s failure was poor inter-service communication, and the fact that fighter pilots had not been informed that Tirpitz had been moved off Håkøya a couple of weeks earlier.
Tirpitz had previously survived some 19 bomb hits, including one 12,000-lb (5443-kg) and five 1,600-lb (726-kg) weapons, in air raids which had cost the British 13 Royal Air Force and 19 Fleet Air Arm aircraft.