enigmas - and other recovered artefacts - of U-85, The

Cryptologia, Apr 2003 by Hamer, David H

The wheels installed in M2946 are, left to right, B/Beta, V, VIII, IV. The Ringstellungen are respectively AYCM. The external wheel positions at the time of recovery, and presumably at the moment of attack, were OQLN. We can thus account for seven of the eight wheels used with M294610.

The Stecker, or plugs, are still in position in the plugboard showing that at the moment of the sinking of U-85 the six 'self-steckered' letters were: A, C, L, O, R and U. Because the connecting cords have been eaten away by seawater corrosion, the actual Stecker pairings remain unknown.

The complete wheel cage of M3131 is shown in Figure 9. The wheel positions upon recovery were recorded as QVUB. The wheels left to right, are B/Beta, II, V, VII and the Ringstellungen are AJTU, respectively. This accounts for all eight wheels of M313111.

Thus, 15 of the 16 regular wheels that one would expect to find in U-85's inventory are accounted for12. To date no spare Zusatzwalze or Umkehrwalze has been recovered but since the sinking of U-85 occurred only two months after the introduction of Enigma M4 and the C/Gamma combination did not come into use on Triton until 1 July 1943 it is probable that these items were not included in U-85's inventory.

THE CODEBOOK

During an earlier dive, on 20 June 2001, a large block of silted material that contained a codebook was recovered from the sonar room. With enormous difficulty this was brought to the surface. Unfortunately much of the codebook was lost during this operation. A title page was recovered but regrettably it is not clear if this page refers to the entire codebook or simply to a section of something much larger in scope (though its position in the book suggests the latter). A rough translation13 of this page is:

Appendix

Semaphore

Between German war- and German merchant ships

(By order of the Naval High Command)

A page of the codebook, approximately 27 x 20 centimeters, is shown in Figure 10 with details of another page in Figure 11. Another title page says:

Medical section

(send)

In this section meanings of flag signals with a medical content are arranged alphabetically by reference to the decoding tables. This enables signal traffic to be handled rapidly in case of sickness and accidents. These signals are no longer included in the general dictionary of the sending tables.

Recovered pages of the codebook span the range 650 to 780 and obviously represent only a fraction of the complete book. The Winkspruchverfahren (semaphore) title page is identified as the entry to an appendix. Apparently this volume included unrecovered sections. It is interesting to speculate as to their possible content.

MESSAGE PAD

On 28 September 2001 a message pad - overall dimensions 31 x 23 centimeters - was recovered from the sonar room. Detail from the message pad is shown in Figure 12 and begins:

Cipher-pad Secret (after being used)14

SUMMARY

Divers have recovered artefacts from U-85 that show that at the time of its sinking the U-boat was equipped with two Enigma M4 with serial numbers M2946 and M3131. Each was provided with a full complement of eight regular wheels (I-VIII) and at least a B/Beta Umkehrwalze /Zusatzwalze combination. The internal setting of each of the two Enigmas at the time of U-85's sinking was determined. M2946 was connected to an electric typewriter that acted as a printing device.