Admiralty Bigram System |
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| U-boats were referred to by the OICs in one of three ways: | ||||||||||||||||||||||||||||||||||||||||||||||
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Much of the content of Admiralty-COMINC serials was devoted to correlating these three references in order to track a given U-boat. The primary source of information used by the Admiralty OIC to track U-boats was intercepted U-boat communications. These messages were most often addressed to the CO by name. Typically when a CO's name first appeared in message traffic the boats hull number was uncertain. In these cases the Admiralty would allocate a vacant temporary bigram in the series XA to YZ. When the boat's hull number was identified the temporary bigram would be vacated in favor of the one previously associated with that boat and used by the OICs from that point on during its patrol. |
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| For example, the bigram CK was allocated to U-333 from the time she first left home waters until she was sunk 31-Jul-44. U-333 departed La Pallice 2-Jun-43 Kapitänleutnant Cremer's name soon appeared in message traffic. On 13-Jun-43 the Admiralty allocated the temporary bigram XY to Cremer. On 15-Jun-43 the Admiralty identified XY as CK U-333 Cremer and vacated the temporary bigram XY. Hence forth, on that patrol the boat was referred to in the serial messages as CK. | ||||||||||||||||||||||||||||||||||||||||||||||
| If a U-boat were sunk (liquidated in Admiralty terms) the Admiralty would vacate the associated bigram and it might be assigned to another U-boat. For example the bigram AA was assigned to U-94 from 20-Nov-40 to 28-Aug-42, to U-964 from 30-Sep-43 to 16-Oct-43, and to U-2511 from 17-Mar-45 to 6-May-45. | ||||||||||||||||||||||||||||||||||||||||||||||
| Admiralty assigned bigram series | ||||||||||||||||||||||||||||||||||||||||||||||
| When a boat left home waters OIC Admiralty would assign a vacant bigram whose first letter was from the table below. The second letter of the bigram would be in alphabetical sequence from the list of vacant bigrams. So for example if a new 500-ton U-boat was known to have deployed and all the "A" series and "C" series bigrams were in use, OIC Admiralty would assign the boat the bigram EA and the next unidentified 500-ton U-boat EB and so on. Hence forth, this bigram would be used for tracking purposes | ||||||||||||||||||||||||||||||||||||||||||||||
| Boats operating in the Arctic or Baltic were not assigned bigrams but were referred to in serials as ON or OB respectively. Bigrams were not assigned If operating in the Mediterranean but a boat might be referred to by the bigram allocated during previous Atlantic operations and or the hull number might be followed by an M. | ||||||||||||||||||||||||||||||||||||||||||||||
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| A new system of bigrams was introduced in November 1944 | ||||||||||||||||||||||||||||||||||||||||||||||
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| Bigram search engine | ||||||||||||||||||||||||||||||||||||||||||||||
| In order to make the serial messages as readable and useful as possible, the administrator developed a bigram database. Mike Holdoway, the administrator of the Convoy Web website, programmed a search engine which makes it possible to search the database and determine which U-boat is under discussion in a given message. The bigram search engine is found at the bottom of this page and on each page of the serial messages. Type in a bigram, hit the FIND BIGRAM button and the search engine will display a response listing the U-boats and dates that bigram was in force. | ||||||||||||||||||||||||||||||||||||||||||||||
| The bigram database is based largely on the serial messages between Admiralty and COMINCH OICs and does not cover the period prior to May 1942. Unless the allocation or vacating of a bigram is mentioned, some guesswork is involved in assigning the start and stop dates. If they the are are not specified in the serial messages, it is assumed that the bigram was generally allocated at the time the U-boat left home waters. The stop date is assumed to be the date of loss. The OICs often discussed the movements or loss of a boat long after it was sunk so keep this in mind when using the database. | ||||||||||||||||||||||||||||||||||||||||||||||
| The administrator is continuing to expand and refine the bigram database. I wish to thank U-boat researchers Ken Dunn and Axel Niestlé for their help in this effort. | ||||||||||||||||||||||||||||||||||||||||||||||
Click the icons to view the associated records |
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Proceed to the COMINCH - Admiralty Serial Messages page |
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