The work of RAF Coastal Command aircraft engaged in anti U-Boat patrols was long and for the most part uneventful. Day after day they made sweeps far out into the Atlantic, the crew constantly scanning the ocean for any sign of the lurking threat to Allied shipping. Weeks or months might pass before they were called into action.
To catch a U-boat on the surface was a rare event. To be able attack a U-boat before it had any chance to defend itself was rarer. To disable the boat on the surface was exceptionally rare - it appears to have been a unique event.
Such was the fate of U-570 on 27th August.
The following summary of the incident was made by Naval Intelligence following the interrogation of the crew:
At approximately 0830 on the morning of 27th August, 1941, "U 570" submerged in position about 62° 15' N. and 18° 35' W. to obtain some respite from heavy seas which had already caused much seasickness among her inexperienced crew.
At 1050 the captain decided to surface again and brought the U-Boat up from a depth of approximately 90 ft. What happened next can only be attributed to the lack of training of the Commander. Rahmlow entirely forgot to make any observation for hostile aircraft before exposing his ship.
It so happened that a Hudson aircraft "S" belonging to 269 Squadron, and piloted by Squadron-Leader Thompson, was almost immediately overhead. "U 570" perceived her danger too late and, while she was attempting to crash dive, the aircraft dropped a stick of four 250 lb. depth charges, at an angle of 30° to the U-Boat's track. These exploded close to her, the nearest being about 10 yards away. One minute after the water disturbance had subsided "U 570" surfaced again, bow down, and 10 to 12 of her crew came on deck. The aircraft attacked with guns until a white flag was waved from the conning tower.
‘The detonation of the depth charges, the smashing of instruments, the formation of gas, thought by the crew to be chlorine gas, and the entry of a certain amount of water apparently convinced Rahmlow that his boat was lost’
It was established by interrogation of prisoners that, at the moment of the attack, confusion reigned within the U-Boat. The detonation of the depth charges, the smashing of instruments, the formation of gas, thought by the crew to be chlorine gas, and the entry of a certain amount of water apparently convinced Rahmlow that his boat was lost, for her ordered the crew to don life-jackets and mount the conning tower.
Prisoners stated that once on deck it became necessary for them to wave the white flag, as it was possible that the aircraft, imagining that they were about to man their gun might have attacked once more. Seas were apparently so high, that the manning of the gun was out of the question, as also was the launching of a boat, and no-one among the crew relished the prospect of being cast into the seas, when not a single ship was in sight. Huddled in their miserable position the crew remained throughout the day.
At 1345 the Lockheed aircraft was relieved by a Catalina Flying Boat, which, like its predecessor, proceeded to circle the U-Boat with its guns trained on the crew. As the day drew on "U 570's" officers seem to have regained some of their composure, and a number of men re-entered the U-Boat. A wireless signal was sent informing the Vice-Admiral U-Boats that the U-Boat could no longer submerge and that she had been captured. After this unskilled attempts were made with a hammer to smash vital and secret mechanisms.
Confidential papers were dumped over the side, and the cipher machine was broken to pieces and also dumped. Water was rising in the control room and, after working the electric pumps, current ran low and the lighting failed. The forward compartments were shut off because of leakage.
At 2250 the aircraft and "U 570" were sighted by H.M. Trawler "Northern Chief." This vessel closed the U-Boat and made the following signal: "If you make any attempt to scuttle I will not save anyone, and will fire on your raft and floats." The reply was made: "I cannot scuttle or abandon; save us to-morrow, please."
The U-Boat was then ordered to show a small white light to ensure that contact might be maintained, and this was fitted aft. The crew of "U 570" were still apparently anxious about their fate and began to jettison ammunition and provisions in order to lighten ship. Many of the men appear to have gone below to recover their most precious possessions, and one or two prisoners have stated that they actually slept below on this night.
As usual Naval Intelligence were very interested in the morale of the crew and details about their training etc. On this occasion the prisoners were quite forthcoming:
The chief petty officer, and to a lesser extent, some of the petty officers, expressed great concern at the inadequacy of the training and the lack of U-Boat experience, not only of the men, but also of the officers and petty officers; no attempt was made to disguise the incompetence of the crew and the officers were severely criticised by all the men.
The impression gained was that the morale of the ratings was high at first, as they had been filled with clever propaganda about the glammour of belonging to the crew of a U-Boat, and they had little or no realisation of active service conditions; many were helplessly seasick, and, at the first sign of real action, they gave way to panic and became useless, admitting later that they were, in point of fact, glad to be out of the war; they were somewhat childish in many ways and appeared to have forgotten their recent escape from death, as they became interested in and curious about their immediate future prospects.
For much more on the capture of U-570, including reports and photographs made by the U.S. Navy, see U Boat Archives.