At 10:00 p.m. on May 24, 2016, the aircraft carrier HMS Victorious launched nine Fairey Swordfish torpedo bombers against the battleship Bismarck. made a single torpedo hit under the bridge. However, up against strong belt armour and torpedo bulges, they failed to cause substantial damage. The attacking aircraft were all safely recovered by Victorious, despite poor weather, darkness, aircrew inexperience and the failure of the carrier's homing beacon.
The British ships were beginning to run low on fuel, and the escape of Bismarck seemed more and more certain. However, at 10:30 am, on 26 May, a Catalina flying-boat, based at Lough Erne, Northern Ireland, found Bismarck. This contact was taken over by two Swordfish from Ark Royal.
Ark Royal then launched an air strike, but her aircrew were unaware of Sheffield's proximity to Bismarck, mistook the British cruiser for the German battleship and therefore immediately attacked her. Their torpedoes had been fitted with influence detonators, and several of them exploded prematurely. Others missed their target, and the attacking aircraft then received a warning from Ark Royal that Sheffield was in the vicinity, whereupon the Swordfish finally recognized the cruiser and broke off the attack.
Ark Royal now launched, in almost impossibly bad weather conditions for air operations, and from a distance of less than 40 miles upwind of Bismarck, a second strike consisting of 15 Swordfish. These were carrying torpedoes equipped with the standard and reliable contact detonators. The attack resulted in two or three hits on the German ship, one of which inflicted critical damage on her steering. A jammed rudder now meant she could now only sail away from her intended destination of Brest. At midnight, Lutjens signaled his headquarters: "Ship unmaneuverable. We shall fight to the last shell. Long live the Führer."
At 1450, after a meticulous briefing during which the strike commander, Lieutenant-Commander J. A. Stewart-Moore, was specifically informed that only Bismarck was in the target area, the 820 Squadron Officer Commanding (OC) led the strike off. At 1520, the strike group detected a target on ASV radar; some twenty miles closer than expected. Knowing that only Bismarck herself was in the target area, Stewart-Moore began his attack approach and, at 1550, the Swordfish burst out of the bottom of the cloud cover and commenced their attack. It was readily apparent that they had totally surprised their foe, as there was quite literally, no AA fire. With devastating swiftness the Swordfish descended from all points of the compass dropping their deadly cargoes. Only after 11 had released did the true reason for the lack of defensive fire become apparent; they were attacking HMS Sheffield!
The Swordfish aircraft from HMS Ark Royal very quickly joined the battle. Unfortunately they had not been advised that the cruiser HMS Sheffield was on the scene and in their first attack launched all their torpedoes at her. Only good fortune prevented an epic Royal Navy disaster because the magnetic torpedoes failed to explode. A second attack was soon launched, with torpedoes fitted with contact detonators, and this time found the Bismarck. John Moffat was piloting one of the Swordfish as it came round to attack.