A Rare Edition of the "Signal Key for the Radio Signal Service", For Enigma Use,

German, 1939,

Footnotes

Provenance:
German Naval Training Command, Archive Directory stamp (inside front cover).
German Fleet Base Command, Department of Service Regulations, Archive Directory stamp (inside front cover).

The present Lot is one of the earliest wartime versions (October 1939), produced only one month after the start of the war, for implementation from the 14th January 1940. October 1939 coincided with the first U-Boats heading out into the Atlantic to begin operations.

The previous edition was declared expired upon the issuing of this updated version. As it was was produced before 1942, the codes would have been produced exclusively for M3 Enigma encryption machines. Due to the lack of annotated or missing pages, this particular signal book would likely have been used at a land-based submarine command centre, or provided to an operative for use in a specific month. To ensure that the radio signal key was consistent between all bases and ships, modifications to the radio signal key or equipment were expressly forbidden.

German Enigma codebooks from World War II are among the rarest printed wartime material. Of these codebooks, those relating the Kriegsmarine are even more scarce, as many of these signal keys were printed on water-soluble paper. Land-based naval headquarters were similarly well-prepared, with all commanders under strict orders to destroy their Enigma machines and any accompanying codebooks in the event of imminent capture. This Signalschlüssel instructions state that the codebook must be 'effectively destroyed by fire' or 'sunk in deep water'.

The use of Engima machines and codebooks sought to avoid covert communications from ship to land being intercepted by Allied planes and other watching points. Morse Code was already vulnerable to interception, and the Allies had evolved a High Frequency Direction Finding system (HFDF) which could track the position of a message source. When Enigma machines were adopted by the German military, the use of short length signals minimised the possibility of the source being located by HFDF.

Approximately seven hundred U-Boats were sunk at sea over the course of the war, and most of the remaining three hundred were scuttled by the German Navy in 1945. It is therefore exceptionally rare for examples of any type to come to market, with notable codebooks sold at Bonhams, June 2018 ($225,000) and Bonhams, June 2014 ($146,500).