- Arundel, Richard, Captain, RAN Rtd
- RAN operations, Ship histories and stories, WWII operations, History - WW2
- RAN Ships
- None noted.
- June 2007 edition of the Naval Historical Review (all rights reserved)
The article ‘Reflections on the Sydney/Kormoran Battle 1941‘ in the December 2006 Naval Historical Review, referring to an interview with the now ninety-two year old Radio Communications Officer of the German raider, invites me to respond with another, and as yet unresolved, aspect of the engagement.
When an ex-Director of Naval Communications, CDRE Ian Nicholson, CBE RAN Rtd., became ill in the early 1990s, he bequeathed to me a request for further research into his belief that Sydney’s deception and loss was based upon the compromise of the Allied Mership Secret War Callsign Book.
The German Admiralty had gained considerable tactical experience with their raiders in WWI, and this was put to good use in the early days of WWII. By the end of 1940 six raiders had disposed of 54 Allied merchant ships. Prior to the outbreak of that war, the German Naval Intelligence Service was fully aware of Allied code and cipher systems and consistently read and deciphered most British circuits until machine ciphers were introduced later in the war. There is ample evidence that the German navy trained its specialist signal officers, in particular those selected for its HSK raiders, in merchant ship intercept plot techniques, warship radio signal identification, evasion tactics and signal deception. Evasion and deception would have been the most vital tactical radio skill that Fregattenkapitan Detmers would have rehearsed with the many intercept scenarios in his raider survival armoury. Furthermore his ship’s complement included 24 communicators.
Several visits to the German War Archives in Freiburg and the extensive Public Record Office in Kew, London, indicated that the German High Command, through its agencies, had briefed its raiders in depth about Allied single and multiple ship convoy systems and in particular communication arrangements. The use of secret war callsigns would have been further confirmed through interceptions of broadcast and ship-shore radio communications. Quite obviously it would have been a top priority to obtain a copy, or extracts, of the Allied merchant ship secret callsign book for selective use by raiders as part of their in extremis disguise if trapped and challenged by a more powerful enemy. That such a compromise existed would have been one of the German navy’s most highly protected and never-to-be-revealed secrets, since every raider’s survival depended upon the secrecy of such a compromise. Only a select few officers would have been privy to this crypto secret.
Merchant ships would have been given their individual war callsigns in sealed orders. Only major warships would have been issued a complete merchant ship code/decode secret Callsign book that would be amended periodically with issues of strictly controlled sealed orders and confidential book amendments. These issues would be sent to area Distributing Offices for onward despatch to warships whilst merchant ship sealed orders would be routinely checked at War Ports. Thus how could a compromise of the Master Mership Secret War Callsign book, or extracts, occur?
Other than the rare instance of cryptographic book recovery from sunken ships such as a submarine in close proximity to enemy territory, e.g. HM S/M Seal, a likely example could be as follows. Merchant ships were often fitted with a special vault to transport classified materials to Distributing Offices, such as Singapore, when a King’s Messenger would accompany vault material. So far as the writer knows, GCHQ has never released details of merchant ships captured by German raiders where there may have been a compromise of classified material. Take the case of MV Automedon captured and sunk close to Singapore by HSK Atlantis on 11 November 1940.
Atlantis was also disguised as a Dutch vessel. Automedon accompanying King’s Messenger, Captain M. F. L. Evans, a ship’s master, was knocked unconscious by Atlantis’s gunfire and when he had recovered, found his vault had been blown open. Atlantis’s English interpreter realized he had unearthed a treasury of highly classified documents including some codes and ciphers that were spirited to Tokyo and thence to Berlin. (Curiously the cache included a Chiefs of Staff report approved by the War Cabinet and destined for Air Marshall Brook-Popham, C-in-C Malaya, on how to conduct a likely campaign in South East Asia against the Japanese should they invade Malaya! Brook-Popham was not told of this report until after the war. That British Intelligence eventually knew of the compromise was never released to, inter alia, Australia, until well after the attack on Pearl Harbour. This document was traded with the Japanese for better liaison with German shipping and may have contributed strategically to the attack on Pearl Harbour. If the Australian Government had known about this compromise, one also wonders whether our troops would have been so sacrificed in Malaya.)