After being commissioned in December 1941 U-335 had spent the first half of 1942 ‘working up’ as her crew of 44 men familiarised themselves with life on a U-Boat. Most operational U-Boats were based in western France – with direct access to the Atlantic. U-boats on passage to the French bases had to travel all the way round Britain – the greater part of the journey being made on the surface. Inevitably the Royal Navy would be looking for them in the North Sea.
On 1st August 1942 U-335 left Germany on her first operational patrol. She made just one practice dive and continued her journey north. 42 men out of 44 probably never knew what hit her on the evening of the 3rd August:
‘U 335’ had been on the surface for about six hours when at 2128 B.S.T., H.M.S. ‘P.247’ [Subsequently renamed HMS/M Saracen] sighted her fine on the starboard bow at 3,000 yards range. ‘U 335′ was then making seven knots, 310°, in position 62° 48′ N., 00° 12’ W. [North Sea midway between Faeroes and Norway]
[Matrosengefreiter – Ordinary Seaman – Rudolf] Jahnke was one of the look-outs at the time, his sector being right astern to Red 80. Some five or six others were also on the bridge.
Having sighted the U-Boat, ‘P.247’, who was throughout at periscope depth, altered course from 030° to 015° and at 2131-1/2 fired six Mark VIII torpedoes from tubes 1 to 6. It was possible to fire so soon after sighting as all tubes had been kept flooded and firing reservoirs charged throughout the patrol.
The torpedoes were fired at seven second intervals, the range of the target then being 2,500 yards. At 2133-1/2, a torpedo struck ‘U 335’ abaft the conning tower and she vanished.
At 2137 ‘P.247; surfaced and sighted a large area of oil fuel and wreckage. Two survivors were seen in the water, but one refused to be rescued and was drowned. Jahnke himself was taken on board at 2150, suffering badly from shock and a surfeit of fuel oil, but recovered quickly from both.
Two attempts were made to interrogate him but without result. He remained on board until “P.247” returned to harbour on 11th August; he was accommodated in the E.R.A.s’ mess, where he behaved well and proved quite friendly and talkative, but let slip no information.