One of the outstanding intelligence break-throughs of the war came on 9th May with the capture of an intact Enigma machine, the German encoding device that they believed to be impossible to break. The British had assembled a team of brilliant academics at Bletchley Park who were making steady progress with the task of deciphering German messages encoded with ‘Enigma’ machines. They already possessed one Enigma machine, passed on by Polish Intelligence before the war. What was needed were the internal rotors in the machines that were currently being used. A number of schemes had been devised to capture these but the boarding of U-110 came as an unexpected bonus.
The U-boat had been forced to surface after depth charging, the crew had abandoned ship believing that the U-boat was already sinking. The surviving crew were rescued and quickly taken below decks so that they would not be aware that the boat was to be boarded. The commander of the boat Lemp died, possibly shot as he attempted to swim back to the boat to sink her.
The Captain of HMS Bulldog reported:
H.M.S. Bulldog stopped within 100 yards of the submarine and sent away an armed whaler’s crew. No sign of a white flag was seen and two men appeared to be manning the submarine’s forward gun. Fire was again opened by Lewis gun and two or three men were hit. My object was to keep the crew rattled. They already appeared dazed and uncertain what to do. By the time the whaler was alongside the submarine, the whole crew appeared to have jumped into the water. There was a moderate sea running and waves were breaking over the U. boat’s deck. The officer in charge of the whaler, appreciating the necessity of speed, ran his boat hard on board the submarine and a wave carried it on to the deck where it was smashed. The crew found that the conning tower hatch was closed. They opened it and went below without delay. ( Their orders were to seize all books and anything that looked important). Shortly afterwards they signaled that the U. boat had been abandoned, and appeared to be sound and in no danger of sinking.
Sub-Lieutenant David Balme reported how he boarded U-110:
At 1245 9th May, I left [HMS] Bulldog in charge of a boarding party to board an enemy submarine which had surfaced. The crew consisted of 6 seamen, 1 telegraphist and 1 stoker. “Bulldog” was lying to windward of U boat and there was a heavy swell running so to save valuable time I made for the weather side (Port).
There were numerous holes in the Conning Tower casing caused by “Bulldog’s” 3″ and Pom-pom. As no small arm fire was opened up at the whaler from the U boat, I was fairly confident that there was no one in the Conning Tower. This proved correct after having entered conning tower through opening on starboard side. The hatch down was closed tight. (This hatch was 18″ to 24″ in diameter, spherical surface with wheel for screwing down; on unscrewing this the hatch sprung open as soon as a clip was released).
I went down the ladder to the lower Conning Tower where there was a similar closed hatch. On opening this hatch I found the Control Room deserted! hatches leading forward and aft were open and all lighting on. On the deck there was a large splinter from the conning tower. There was a slight escape of air in the control room but no sign of Chlorine so gas-masks which had been taken were now discarded. So also were revolvers which now seemed more of a danger than an asset.
The U-boat had obviously been abandoned in great haste as books and gear were strewn about the place. A chain of men was formed to pass up all books charts etc. As speed was essential owing to possibility of U boat sinking (although dry throughout) I gave orders to send up ALL books, except obviously reading books, so consequently a number of comparatively useless navigational books etc were recovered.
All charts were in drawers under the chart table in the Control Room; there were also some signal books, log books etc here. The metal sheet diagrams were secured overhead. Meanwhile the telegraphist went to the W/T office, just forward of the control room on starboard side. This was in perfect condition, apparently no attempt having been made to destroy any books or apparatus. Here were found C.B’s., Signal Logs, Pay Books, and general correspondence, looking as if this room had been used as ship’s office.
Also the coding machine was found here, plugged in and as though it was in actual use when abandoned. The general appearance of this machine being that of a type writer, the telegraphist pressed the keys and finding results peculiar sent it up the hatch. This W/T office seemed far less complicated than our own-sets were more compact and did not seem to have the usual excess of switches, plug holes, knobs, ‘tally’s’ etc on the outside.
An attempt was made to take U-110 under tow for the 400 mile trip back to the nearest base on Iceland but she sank the next day.
The original British reports are available online at U Boat Archive.