The Imitation Game - TURING and the BIGRAM TABLES from U-110

TURING and the BIGRAM TABLES from U-110 (Illustration) World War II Film World History Ethics

One way convoys crossing the North Atlantic could protect themselves, and the supply-carrying ships they were escorting, was to drop depth charges against lurking German submarines. This image depicts such an event during the Battle of the Atlantic. Online via the Library of Congress, the photo is circa 1943. Note the merchant ship (appearing mid-left in the image). Click on the image for a better view.


U-110 had successfully attacked convoy ships, en route to Britain, when the German submarine met its own fate.  It was an event more meaningful for Britain than the Royal Naval officers understood at the time.

Georg Högel was aboard U-110 when it was attacked by His Majesty's Ships Bulldog (H-91), Broadway (H-90) and Aubretia (K-96).  He recalls what it was like when depth charges rocked his U-boat:

The light went out and we found ourselves sitting in the dark.  Only the emergency lights came on.  We then tried to restore power and check for water leaks.

The classic attack on U-boats - send down depth charges and cause the vessel to surface - actually worked in the attack on U-110.  Instead of sinking, as so many submarines did after depth charges were deployed against them, U-110 came to the surface.  

The surfaced boat contained the secret bigram tables which Alan Turing desperately needed to make further progress in cracking Germany’s naval Enigma code.

Högel continues with his recollections of that May, 1941 day:

We were inside the U-boat and had no idea what was going on above us.  But the commander on the bridge kept shouting: “Get out! Get out!”

We asked: “What shall we do with the secret papers?”

The order came back to leave everything and simply try to get out.  

I don’t know - but we can’t be blamed for following orders.  You can’t imagine what it was like if you weren’t there. 

Following their orders, U-110's crew abandoned ship, leaving their Enigma code books behind.    

Högel had one book he wanted to rescue, however.  It was a book of love poems to his girlfriend.  He went back for it:

I went back down and grabbed the key to the place where the books were kept, and where mine was.  I got my book out and tried to put it in my pocket.  But it didn’t fit, it was too big.  So I unbuttoned my shirt and shoved it in there.  It lay against my chest and that’s how I swam for half an hour.

When David Balme and his boarding party came aboard the stricken U-110, they began to search the vessel.  They had no idea about the Enigma machine, or its secret codes, or the much-needed bigram tables (which the Germans called Doppelbuchstabentauschtafel meaning, in English, "double-letter conversion table”). 

The boarding party had no idea what to search-for.  Balme had never heard of Station X or what anyone was doing at the old Bletchley Park mansion.

While he was seated at the Captain’s desk, Balme came across a sealed envelope.  He didn’t open it and, even if he had, he wouldn’t have understood since he did not speak German.  He thought it must have been important because it was sealed and in the Captain’s desk.

He placed the envelope into his pocket, without having a single clue that what he had discovered was exactly what Alan Turing needed.

Balme also didn’t know another key factor about the Enigma code books. The ink would immediately fade if the code books got wet. That is why, if U-boats were captured, the crew typically threw the code books overboard. It was an effective way of keeping the secrets out of enemy hands.

This code book, however, made its way into enemy hands.

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Author: Carole D. Bos, J.D. 5197stories and lessons created

Original Release: Dec 31, 2014

Updated Last Revision: Jun 02, 2016

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"TURING and the BIGRAM TABLES from U-110" AwesomeStories.com. Dec 31, 2014. Jun 01, 2020.
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