Currier, Prescott. "My 'Purple' Trip to England in 1941." Cryptologia 20, no. 3 (Jul. 1996): 193-201.
The author was a member of the team that traveled, Purple machine in hand, to GC&CS at Bletchley Park in January 1941. He argues that the trip was a great success: "Even though we did not in fact bring back an Enigma, we brought back all the information we really wanted and there was never any question that anyone was holding anything from us."
Denniston, Robin. "Research Note: Yanks to Lunch -- An Early Glimpse of Anglo-American Signals Intelligence Co-operation, March 1941." Intelligence and National Security 11, no. 2 (Apr. 1996): 357-359.
Urinary tract operations on GCCQ's operational head at Bletchley Park, Alastair Denniston, may well have forestalled one of the earlier efforts (the Sinkov visit) toward Anglo-American cooperation in the Sigint arena.
Erskine, Ralph. "Churchill and the Start of the Ultra-Magic Deals." International Journal of Intelligence and Counterintelligence 10, no. 1 (Spring 1997): 57-74.
Erskine sucks dry available materials and concludes that "allegations of a double-cross or broken deal by 'perfidious Albion' [during the Sinkov mission in February and March 1941] are without the slightest foundation."
Erskine, Ralph. "The Holden Agreement on Naval Sigint: The First BRUSA?" Intelligence and National Security 14, no. 2 (Summer 1999): 187-197.
The author suggests that the Holden Agreement of 2 October 1942 between the U.S. Navy and GCCS "probably has a stronger claim than BRUSA to being the forerunner of the UKUSA Agreement." It was the first agreement "to establish the special Sigint relationship between the two countries," and "it set the pattern for UKUSA, in that the United States was very much the senior partner in the alliance."
Erskine, Ralph. "The 1944 Naval BRUSA Agreement and Its Aftermath." Cryptologia 30, no. 1 (Jan. 2006): 1-22.
This article has substantial detail on how the U.S.-British agreements were implemented. Erskine concludes that "GCCS was, on the whole, disappointed with the arrangements for sharing Japanese naval Ultra during the war." He notes, however, that "[p]oor communication facilities on the British side badly held up the implementation of the Agreement." The article includes three appendices: "The BRUSA Agreement: 14th January 1944"; "An Agreement between G.C.&C.S. and Negat [OP-20-G] on Japanese Naval Cryptanalytic Tasks," dated 23 October 1944; and "Proposals Made to OP-20-G on 4th June 1945 for British Sigint Effort on S.E.A.C. [Mountbatten's South East Asia Command]."
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.
Gladwin, Lee A. "Cautious Collaborators: The Struggle for Anglo-American Cryptanalytic Co-operation, 1940-43." Intelligence and National Security 14, no. 1 (Spring 1999): 119-145. And in Allied and Axis Signals Intelligence in World War II, ed. David Alvarez. London: Frank Cass, 1999.
Gladwin covers the developing Anglo-American relationship from the earliest contacts through the British and United States Agreement (BRUSA) of 1943.
Jenner, C.J. "Turning the Hinge of Fate: Good Source and the UK-U.S. Intelligence Alliance, 1940-1942." Diplomatic History 32, no. 2 (2008): 165-205.
Note from Royal Historical Society Database: "The diplomatic mission of American Colonel Bonner Fellers to Cairo in 1942 and the security breach that occurred."
Kahn, David, ed. "From the Archives: Britain Reveals Its Bombe to America." Cryptologia 26, no. 2 (Apr. 2002): 124-128.
Memoranda from "C" (Admiral Sinclair) and Alastair Dennison make it clear that the early 1941 U.S. delegation was told of the existence of the bombes.
Kruh, Louis. "British-American Cryptanalytic Cooperation and an Unprecedented Admission by Winston Churchill." Cryptologia 13, no. 2 (Apr. 1989): 123-134.
Included here is correspondence between Churchill and Roosevelt documenting that the British had decrypted American diplomatic traffic.
MacKinnon, Colin. "William Friedman's Bletchley Park Diary: A New Source for the History of Anglo-American Intelligence Cooperation." Intelligence and National Security 20, no. 4 (Dec. 2005): 654-669.
In late April 1943, Friedman, Col. Alfred McCormack, and Lt. Col. Telford Taylor traveled to Great Britain to meet with British cryptologists. His diary of that visit, which lasted until 12 May 1943, "is a meticulous account of his activities during the mission." It was in the same period that the 1943 Travis-Strong Agreement was negotiated. and it appears the U.S. delegation was part of that process. See also, Erskine, "William Friedman's Bletchley Park Diary: A Different View," I&NS 22.3 (Jun. 2007): 367-379.
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