UNITED KINGDOM

World War II

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The designator "ISOS" (Intelligence Series Oliver Strachey) was used for "all decrypts of Abwehr signals, however enciphered, to disguise the breaking of Abwehr Enigma." Erskine, I&NS 12.3/124, fn. 16.

Erskine, Ralph. "The Admiralty and Cipher Machines during the Second World War: Not So Stupid after All." Journal of Intelligence History 2, no 2 (Winter 2002): 49-68. [http://www.intelligence-history.org/jih/previous.html]

From abstract: "[T]he British official history of intelligence's claim that 'by 1939 the Admiralty had rejected the use of the [British cipher machine] Typex machine in ships' is categorically wrong -- only slow production prevented Typex entering service on ships.... The article explains why Typex (which was an improved version of commercial Enigma) was much more secure in practice than Wehrmacht Enigma, and describes the development of the Combined Cipher Machine (CCM) for joint use by the US, British, and Canadian navies. The CCM, and a post-war NATO version, are shown to have been very insecure, but wartime German codebreaking agencies could not break it."

Erskine, Ralph. "Eavesdropping on 'Bodden': ISOS v. the Abwehr in the Straits of Gibralter." Intelligence and National Security 12, no. 3 (Jul. 1997): 110-129.

"This article describes British efforts during the Second World War to counter an Abwehr ship-reporting organization in the Straits of Gibralter, known as the 'Bodden' line, which employed advanced infra-red equipment for night observation purposes."

Erskine, Ralph.

1. "Breaking German Naval Enigma on Both Sides of the Atlantic." In Action This Day: Bletchley Park from the Breaking of the Enigma Code to the Birth of the Modern Computer, eds. Ralph Erskine and Michael Smith, 174-196, 482-488. London and New York: Bantam, 2001.

2. "The First Naval Enigma Decrypts of World War II." Cryptologia 21, no. 1 (Jan. 1997): 42-46.

This article includes both Erskine's commentary and reproductions of "the first text derived from naval Enigma signals" at Bletchley Park. The decrypts are part of the six days of traffic (22-27 April 1940) initially read by the British. It would be early August 1941 before Bletchley would be able to read the main cipher of the Kriegsmarine on an almost continuous basis.

3. "Kriegsmarine Short Signal Systems - And How Bletchley Park Exploited Them." Cryptologia 23, no. 1 (Jan. 1999): 65-92.

This article deals with those short signal systems that "were used by the British codebreakers in Hut 8 at Bletchley Park (BP) as cribs for breaking the two principal [German] naval Enigma ciphers," Heimische and Triton.

4. "Naval Enigma: An Astonishing Blunder." Intelligence and National Security 11, no. 3 (Jul. 1996): 468-473.

Message keys on the German naval Enigma cipher known as Süd, which was used in the Black Sea and Mediterranean, "were doubly enciphered until at least January 1944."

5. "Naval Enigma: The Breaking of Heimisch and Triton." Intelligence and National Security 3, no. 1 (Jan. 1988): 162-183.

6. "Naval Enigma: A Missing Link." International Journal of Intelligence and Counterintelligence 3, no. 4 (Winter 1989): 493-508.

Erskine believes that Hinsley's official history overstates the value of the "find" on U 110.

7. "The Soviets and Naval Enigma: Some Comments." Intelligence and National Security 4, no. 3 (Jul.1989): 503-511.

The article disputes the hypothesis in Geoff Jukes, "More on the Soviets and Ultra," Intelligence and National Security 3, no. 2 (Apr. 1988), 233-247, that the Soviets deciphered Admiral Dönitz' instructions (sometimes called the JW 55B message) to Scharnhorst (Rear Admiral Bey) on 25 December 1943 and that this indicates that the Soviets could break the Naval Enigma.

Glen, Alexander. Footholds Against a Whirlwind. London: Hutchinson, 1975.

Hamilton, C.I.

1 "Human Friction in the British Naval Operational Intelligence Linkages: Bletchley Park-Portsmouth Command, 1942-44." American Neptune 61, no. 2 (2001): 205-220.

2. "The Character and Organization of the Admiralty Operational Intelligence Centre during the Second World War." War in History 7, no. 3 (2000): 295-324.

Hampshire, A. Cecil.

1. On Hazardous Service. London: Kimber, 1974.

According to Constantinides, On Hazardous Service concerns aspects of naval warfare in World War II "that are not too well known and that have features of covertness or of special operations."

2. The Secret Navies. London: Kimber, 1978.

Constantinides says that this book covers selected areas of British special naval operations in World War II. It serves to "shed[] some light on these little-known units and their activities."

3. Undercover Sailors: Secret Operations of World War II. London: Kimber, 1981.

Johnman, L., and H. Murphy. "'The First Fleet Victory since Trafalgar': The Battle of Cape Matapan and Signals Intelligence, March 1941." Mariner's Mirror 91, no. 3 (2005): 436-453.

Kahn, David. Seizing the Enigma: The Race to Break the German U-Boat Codes, 1939-1943. Boston: Houghton Mifflin, 1991. London: Souvenir Press, 1991. New York: Barnes & Noble, 1998.

Kruh, Cryptologia 23.2, notes that the Barnes & Noble edition of "this superb book ... contains a new preface by Kahn, who also used the opportunity to correct some minor errors found in the earlier edition." In the view of Milner, I&NS 9.1, the author presents a "fascinating study ... and a perfectly sound conclusion." He has an "impressive grasp of the practical problems of codebreaking and usage ... [and] understands the limits of special intelligence."

For Surveillant 1.4, this is a "rare gem" of a book. It tells the "story of how the British, unable to break the German naval Enigma cipher machine because it was used in a much more complicated fashion than the Luftwaffe Enigma machine (which they were breaking), had to steal documents from some German weather ships operating north of Iceland, to aid in breaking the codes.... [W]ith these filched documents, [they] were able to break the German U-boat codes and divert their convoys so they wouldn't be sunk and, later, sink the U-boats because they now knew where they were located."

Miller, IJI&C 6.3, says that Kahn "presents another excellent work on intelligence and raises his standards even higher.... This remarkably fine book is the best to date on ULTRA." To Ringle, WPNWE, 17-23 Jun. 1991, the author's "impressive economy and dogged research" has produced "not only great history, but great midnight reading." Peake, AIJ 15.1/90, sees Seizing the Enigma as "a very readable and worthwhile book."

Kingsley, F.A., ed. The Applications of Radar and Other Electronic Systems in the Royal Navy in World War II. Basingstoke: Macmillan, 1995.

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