The North Atlantic seas south of Iceland were relatively calm on May 9th, 1941 as a British convoy made its way from England to Nova Scotia. Escort ships, like the corvette HMS Aubretia, were desperately needed to protect supply ships from the ever-present threat of German U-boats.
In charge of a lurking nearby U-Boat, was Fritz-Julius Lemp (commanding officer of U-110). On board Lemp's ship was a small, portable encryption device used by U-boats to communicate with the German high command. Receiving coded messages on the location of enemy ships, prowling U-boats were constantly on the attack. British supply ships were especially hard hit. The loss of men and supplies was causing a massive strain on Britain's war efforts.
After a lookout on HMS Aubretia saw U-110's periscope, which had been left up, she raced toward the spot where her crew dropped depth charges. Thinking the first batch missed, Aubretia's men dropped more charges. U-110 was struck but not destroyed.
U-110 was now out of control. She had sustained considerable damage: broken vital gauges; ruptured fuel tanks; electrical system failures; and buoyancy tank problems. She shot to the surface, not far off Bulldog's starboard bow. Turning to ram U-110 with one other ship in the convoy, Captain Baker-Creswell suddenly changed his mind. Instead of ramming the crippled sub, why not board her?
Having just experienced a harrowing ride to the surface, the crew of U-110 poured out of the hatch. Under fire from Bulldog and the other ships, they could not man their deck gun. Some jumped, while others fell into the sea, their commander Lemp among them.
Baker-Creswell ordered his boarding party to see what could be found aboard U-110. He placed a 20-year-old sub-lieutenant, David Balme, in charge.
Here is how he recalls those moments as he descended into the bowels of the crippled U-boat:
...I, David Balme, was duty-bound to climb that conning tower and descend into what? Remains of the German crew to greet me? Or scuttling charges rigged to explode as I opened the hatch? My previous seven years of training could not dull the vividness of such mental images.....Stop thinking. Do it,.... I told myself. I climbed the conning tower, and at the top I took my Webley revolver out of its holster. I had never fired it in my life.
I am still haunted by my climb down that last vertical ladder, fifteen feet into the bowels of U-110, now with the revolver holstered. I felt there must be someone below trying to open the seacocks, or setting the detonating charges. But no one was there. There must have been complete panic in U-110, and she was left to us as the greatest prize of the war. But I still wake up at night fifty-six years later to find myself going down that ladder.
Meanwhile the telegraphist found the W/T office [radio compartment] in perfect condition: no one had so much as tried to destroy books or apparatus. Codebooks, signal logs, pay books and general correspondence were all intact. A coding machine, too, was plugged in as though it had been in use when abandoned. It resembled a typewriter, hence the telegraphist pressed the keys, and reported to me that the results were peculiar. The machine was secured by four ordinary screws, soon unscrewed and sent up the hatch to the motorboat alongside.
From there, it would be sent to Bletchley Park where a mathematical genius and his team were already working on a method to crack Hitler's uncrackable code.
Believing their ship had sunk, none of U-110's survivors knew about Balme's boarding party. (They had been quickly brought below deck on the rescue ship.) Four hundred men from the British Royal Navy knew, but not one said a word about U-110's treasure until after the war was over.