Erskine, Ralph. "The Poles Reveal Their Secrets: Alastair Denniston's Account of the July 1939 Meeting at Pyry." Cryptologia 30, no. 4 (Oct. 2006): 294-305.
Erskine provides both the document and commentary on "the only British first-hand account of the historic meeting near Pyry, outside Warsaw, on 26 and 27 July 1939." (footnote omitted) He also includes a letter from Dillwyn Knox to Denniston about the meeting.
Erskine, Ralph. "Ralph Erskine Cracks Open a Tale of the Titans Who Won Key Battle." Times Higher Educational Supplement, 6 Oct. 2006, 24-25.
This article is a review of B. Jack Copeland, et al, COLOSSUS: The Secret of Bletchley Park's Codebreaking Computers (2006), but is worth reading beyond its review purpose for the substantive observations on Tunny that the author has included. Erskine notes that Tunny "was used mainly between the German High Command and army groups," and "provided more strategic intelligence than Enigma . Breaking Tunny traffic was the greatest code-breaking feat of the war. The US Army's reconstruction of Japan's Purple diplomatic cipher machine was comparable to Bletchley's solution of Tunny, but ascertaining Purple's daily settings was relatively simple, while finding Tunny's wheel patterns and settings required the highest cryptanalytic skills and involved advanced statistical techniques and some of the most complex electronic equipment of the war."
1. "U-Boats, Homing Signals and HFDF." Intelligence and National Security 2, no. 2 (Apr. 1987): 324-330.
Sexton sees this as a "scholarly account of the importance of U-boat homing signals and Allied high frequency direction finding (HF/DF) facilities."
2. "Ultra and Some U.S. Navy Carrier Operations." Cryptologia 19, no. 1 (Jan. 1995): 81-96.
Operations by U.S. Navy escort carrier task groups against the German U-boats "show a significant difference of approach in the way in which the United States and British naval authorities employed Ultra (or special intelligence) from naval Enigma -- and escort carriers."
3. "Shore High-Frequency Direction-Finding in the Battle of the Atlantic:: An Undervalued Intelligence Asset." Journal of Intelligence History 4, no. 2 (Winter 2004). [http://www.intelligence-history.org/jih/journal.html]
From abstract: The author "reviews the operations of British and allied shore HF-DF nets during the Battle of the Atlantic." The article "includes Kriegsmarine assessments of shore HF-DF, and describes the measures ... adopted by the Kriegsmarine to counter HF-DF. It shows that shore HF-DF indirectly advanced the breaking of naval Enigma by about 12 months..., and that it was crucial to the breaking of the four-rotor naval Enigma cipher, Triton (codenamed Shark by Bletchley Park), at the height of the Battle of the Atlantic."
Erskine, Ralph. "Ultra Reveals a Late B-Dienst Success in the Atlantic." Cryptologia 34, no. 4 (Oct. 2010): 340-358.
Abstract: "This article describes a B-Dienst success in solving signals using a British code used by merchant ships (the Merchant Ships' Code (Mersigs II)) in late 1943, despite only having a depth of two; it also relates the history of the Mersigs II system."
Erskine, Ralph. "Wehrmacht Enigma Indicating Systems, Except the Kriegsmarine's Kenngruppenbuch System." 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, 444-448, 518. London and New York: Bantam, 2001.
Erskine, Ralph. "What Did the Sinkov Mission Receive from Bletchley Park?" Cryptologia 24, no. 2 (Apr. 2000): 97-109.
This article details the codes, ciphers, and solution methods received by the naval members of the Mission, who were also given the rotor wiring for Wehrmacht Enigma. A "substantial amount of information" was given to the army members about German, Italian, and Russian codes and ciphers but no list of the documents involved is available.
Erskine, Ralph. "William Friedman's Bletchley Park Diary: A Different View." Intelligence and National Security 22, no. 3 (Jun. 2007): 367-379.
The author argues that when Friedman, McCormack, and Taylor traveled to Bletchley Park in mid-1943, the group "had no negotiating authority whatsoever.... Maj.-Gen. George Strong, the US Army's G-2 (intelligence), who had sent them, was absolutely determined to reserve all policy decisions on Sigint to himself." See MacKinnon, "William Friedman's Bletchley Park Diary: A New Source for the History of Anglo-American Intelligence Cooperation," I&NS 20.4 (Dec. 2005): 654-669.
Erskine, Ralph, and Peter Freeman. "Brigadier John Tiltman: One of Britain's Finest Cryptologists." Cryptologia 27, no. 4 (Oct. 2003): 289-318.
The authors term Tiltman "Bletchley Park's finest cryptanalyst on non-machine ciphers." He worked with GCCS/GCHQ from 1920 until his retirement in 1954, but then continued work with GCHQ until 1964. After that, he served as a researcher and consultant with NSA until 1980.
Erskine, Ralph, and Michael Smith, eds. Action This Day: Bletchley Park from the Breaking of the Enigma Code to the Birth of the Modern Computer. London and New York: Bantam, 2001. The Bletchley Park Codebreakers. London Biteback Publishing, 2011.
Beard, I&NS 18.1, says that Action This Day consists of "22 essays covering the BP story from the aftermath of World War I to the era of Cold War cooperation that BP's success made possible.... The editors provide short introductions to each essay, putting them in context." For Rohwer, JIH 2.1, this work contains "a great amount of new information on how things were achieved" at Bletchley Park. "Of special interest are the papers of the B.P. veterans, who reveal not only where they worked, but what they really did and how they achieved their successes."
To Stout, Studies 47.4 (2003), this "collection offers a pleasing combination of scholarship and memoirs." Kruh, Cryptologia 26.2, states flatly that this is "the best book ever written about codebreaking at Bletchley Park.... [C]hapters by some of Britain's outstanding historians, former codebreakers and academics (plus two Americans) ... trace the legacy of BP from the innovative work that led to the breaking of Enigma and other wartime codes, to the invention of modern computng and its influence on Cold War codebreaking."
Christensen, Cryptologia 35.3 (Jul. 2011), notes that The Bletchley Park Codebreakers "contains the material from Action This Day unchanged and includes one new chapter and three new appendices -- all written by former Bletchley Park codebreaker Edward Simpson."
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