May 9, 1941, may have been the turning point of World War II – a full seven months before the United States entered the war. If so, the free world can thank the crews of three British warships; a brand new, but tiny corvette, a 21-year-old former American Clemson class destroyer, and a smallish 11-year-old B-class destroyer
These three ships were part of the 10-ship escorts for Convoy OB 318 in the North Atlantic east of Iceland when they were attacked by several U-boats. The corvette HMS Aubrietia, just 205 feet long and displaying just 940 tons, found a sound contact and dropped a spread of depth charges. To the surprise of the B-class destroyer HMS Bulldog and the Town class HMS Broadway the U-110 popped to the surface. The crews of the Bulldog and the Broadway (the former USS Hunt-DD-194) began peppering the submarine with small arms fire. Even more surprising, the German crewmen began boiling out of the submarine.
The captain of the Bulldog saw an opportunity to capture the submarine. He put together a six-man boarding team as the rescued German crewmen were rushed below decks on the Aubrietia so they could not see what was happening.
Lt. Commander David Balme carefully climbed down the U-boat’s open hatch, fully expecting to be shot by a crewman who had stayed behind to set explosive charges. Another crewman, a telegrapher, searched the submarine’s radio position and found: “a coding machine…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 motor boat alongside.” Two hours later, while eating a sandwich while sitting at the captain’s desk, Balme found the July codes for the machine.
What Blame’s boarding crew had found was an intact Germany Navy Enigma machine used to encode messages, the first operational one captured during the war. Eventually the machine would be packed off to the top secret Bletchley Park where Alan Turing and a team of code breakers used it to help them break and stay abreast of the German naval codes.
Once the code was broken, the British were able to track the locations of German submarines and judiciously order course changes to Allied convoys to avoid some attacks.
The original plan of the Bulldog’s captain was to tow the captured U-110 to Iceland to examine the technology of the Type IX-B, a 9-boat sub-class of a very successful design. Fortuitously, the sub sank while under tow, but without any loss of any British seamen. Had the sub reached Iceland, it seems certain that German spies would have seen it and passed word back to Germany that the sub’s Enigma machine was likely captured.
Instead of examining the submarine, the British got to examine its first Enigma machine. The Germans never realized that their complicated codes were broken. Just how many Allied ships survived because of the capture is unknown. It is known that it was a top British secret. Prime Minister Winston Churchill did not tell President Franklin Roosevelt about the Bulldog’s capture of the Enigma machine until nine months later.
All three of these British warships survived the war. Not a single crewman spoke a word about the capture of the U-110 and its Enigma machine during the war and even decades later out of respect for their duty to remain silent about an important mission.