NSA (National Security Agency) "Eavesdropping On Hell", by Robert J. Hanyok
Historical Guide to Western Communications Intelligence and the Holocaust, 1939-1945
Chapter 2: Overview of the Western Communications Intelligence System during World War II
During the Second World War, the United States and Great Britain operated the principal Western Allied code-breaking agencies. The Commonwealth countries of Canada, Australia, and New Zealand, and Britain’s colony of India provided substantial support with personnel and material, especially in the Middle East, Pacific and Asia theaters of combat. There were lesser contributions from small European national detachments that had escaped from Poland, France, and the Netherlands East Indies. By war’s end, this multinational effort had brought to a high-level of proficiency a worldwide system that intercepted, decrypted, translated, and disseminated intelligence derived from Axis and neutral communications. 
A popular perception about Western communications intelligence and its subsidiary codebreaking function, often generally referred to as “Ultra,” was that this information was available from all Axis and neutral sources at all times to the Allied commanders and leaders. This view is simply not true. The war between the Axis cryptographers to devise and emplace systems to protect their communications and the Allied cryptologists to collect and exploit those same communications (and the mirrored struggle between Allied cryptographers and Axis cryptologists) was marked by victories and defeats on both sides. Although there were major successes by the Allies early in the war, notably the exploitation of some versions of the German Enigma and the Japanese diplomatic machine system, known as Purple, the struggle for cryptologic supremacy was not settled until the midpoint of the war when the full resources of the Allied cryptologic effort finally achieved a general and consistent inroad into most, but still not all, major Axis cryptographic systems. Even then, there remained gaps and shortcomings in the overall Allied capability that produced unpleasant tactical military surprises for the Allies later in the war, such as at the German Second Ardennes Offensive in December 1944. Several Axis and neutral cryptographic systems were never exploited due to a paucity of Allied intercept, the strength of the particular Axis code or cipher, or the late date of a cryptographic system’s introduction into operation. In short, the Ultra success by the Allies was never total or constant when measured in terms of the total number of enemy or neutral codes and ciphers that could be broken or the duration of their exploitation. Where the Allies succeeded was in the exploitation of those Axis communications and cryptographic systems that were critical to the conduct of certain battles and campaigns. This ability also allowed the Allies the ability to gauge the strategic intentions of Berlin and Tokyo in a depth that otherwise would have been lacking if there had been no recourse to the information from Ultra, Magic, and the host of other systems. 
Trying to describe or graphically represent the entire Western COMINT system can be difficult. Some initial attempts were made by the U.S. services. One of the more popular early graphic efforts was a chart devised by the War Department’s G-2 (Intelligence), “A Message from Originator to MIS.” This version was taken from the postwar Army history The Achievements of the Signal Security Agency in World War II and is reproduced here.  It illustrated the system that started with the transmission of a message by an originating entity. It then detailed several intermediate analytic steps to the point where the translation of the original intercept was disseminated to the War Department.
Above: “A Message from Originator to MIS” (Courtesy of National Security Agency)
The system this chart illustrated was limited to those cryptologic functions from intercept to translation that were performed by the Army’s Signal Intelligence Service at Arlington Hall. The chart failed, though, to describe why a certain message was to be intercepted in the first place. There were numerous Axis and neutral radio terminals and networks to intercept. What was the process that determined which one was monitored? Similarly, the chart also left out what happened to the intelligence after it reached the Pentagon. To whom did this information go and how did it get there? Was it handled any differently than intelligence from other sources such as captured documents? In short, the chart failed to explain the place and role of cryptology within the context of the activities of the larger Allied intelligence system.
The production of Allied communications intelligence during World War II was a multistep system. It began with the determination of a hierarchical priority of intercept of Axis communications and was completed with the dissemination of the intelligence derived from it. This system can be likened to a “closed cycle” in which all steps were interrelated. Within this process a significant change to one step affected all the others. For example, a reordering of requirements due to a change in capability or a crisis in a military theater’s situation would affect what was collected and processed. The rise or decline of cryptanalytic effectiveness, efficiency, or advances in technology or techniques could affect what terminals would be monitored in the future and what intelligence gained from them would be disseminated and to whom it would be sent. 
Besides being distinguished by the interdependent nature of its operations, the COMINT system, especially as practiced by the British, was noteworthy for the operational interaction of its analysts That is, individuals at all points in the system contributed information that others could use in their separate jobs. This interaction developed partly from the background of a large number of the individuals who worked in the cryptologic agencies during the war. Many people who worked at Bletchley Park and Arlington Hall were current students, graduates, or faculty recruited from universities and other schools that prized cooperation and an intellectual detachment. And a majority of these hires were women.  More so, the leadership of the cryptologic agencies encouraged the continuation of this free flow of ideas and information. Even those who merely logged in intercepted messages were encouraged to contribute insights and observations.  One high- ranking American observer, who visited Bletchley Park in May 1943, noted that the British personnel approach was “ bold and forward-looking... an imaginable conception of the possibilities of obtaining results from attention to details and infinite pains.”  The result of this approach was a system, which was described by William F. Friedman as “unified at the top and operationally intimate below.” 
The wartime Western Allied communications intelligence system consisted of the following steps: setting requirements, priorities, and division of effort; intercepting messages; processing the intercept; and disseminating the resulting intelligence. Each step consisted of a number of subordinate processes that contributed to its completion, though each process was not employed against every intercept or cryptographic system. Also, each step was affected by a number of technical and institutional constraints, as well as political/strategic influences or contingencies that further determined how effectively a step was carried out. Many of the subordinate processes and the constraints and outside influences for each step will be described in the proceeding sections.
Above: Bletchley Park (Courtesy of National Security Agency)
Two other aspects of the Allied COMINT system need to be considered before we proceed with the description. First of all, when we talk of an Allied system, we are really describing two distinct national systems, that of the United States and Great Britain. While both countries carried out similar communications intelligence activities, we shall see that there were a number of differences between them in organization, security restrictions, equipment, training, and even technical jargon. Like much of the rest of the special relationship between the United States and Great Britain, the wartime Anglo-American COMINT relationship was marked by a search for ways to make the two national systems work in a more cooperative fashion.
Another characteristic of the wartime allied cryptologic agencies was the phenomenal growth experienced by both as the war progressed. In 1939 cryptologic organizations that barely numbered a few hundred were, by war’s end, staffed by tens of thousands of civilians and military personnel. As a representative reg- ister of this massive growth, consider that the U.S. Army’s signals intelligence arm was producing about forty translations a week in January 1942. By the time Japan surrendered, it was turning out about 1,025 translations a week.  Also, during the war, both the GC&CS and the SIS grew organically. They had to design, build, refine, and modify their organizations, equipment, structure, practices, and procedures while they also worked against Axis cryptography and communications. In 1939 American and British COMINT were local cottage workshops. By 1945 they had become a joint global industrial concern.
What follows is a description of the communications intelligence system with a particular eye to the ways in which its operations influenced how it obtained and distributed intelligence about the Holocaust.
 See Euna O’Halpin, “Small States and Big Secrets: Understanding SIGINT Cooperation between Unequal Powers during the Second World War.” Intelligence and National Security (Vol. 17, No. 3, Autumn 2002), 1-16. For more on the relationship with France, see RG457, HCC, Box 1277, Folder 3732, “Liaison with the French on Signal Intelligence Matters,” 28 November 1944; and PRO, HW 14/3, January-February 1940, “Liaison with French and Poles.” For relationship with Netherlands, see PRO, HW 14/18, August 1941, “SIGINT Exchange with Dutch in the Far East.” For more on the relationship with the Poles, see, among others, PRO, HW 14/8, regarding a Polish-manned intercept station in Stanmore, England.
 For example, see Carl Boyd, Hitler’s Secret Confidant: General Oshima Hiroshi and Magic Intelligence 1941-1945 (Lawrence, KS: University Press of Kansas, 1993), pages 57-74, about Axis plans for 1942 and pages 117-139 for German appreciation of the Allied intention in 1944. Also, see Hinsley, Vol. I, pages 429- 493, about COMINT and other intelligence sources regarding German plans and preparations for the inva- sion of the Soviet Union known as Operation Barbarossa.
 SRH-349, The Achievements of the Signal Security Agency in World War II (Washington DC: The Assistant Chief of Staff , G-2, 1946).
 Memorandum for the Deputy Chief of Staff from Major General Clayton Bissell, Subject: Intercept Facilities. 8 September 1944. SRH-145, 200-201. Also Memorandum for Mr. McCloy from Colonel Carter Clarke, no subject 16 March 1944, SRH-145, 158-A.
 For more on the phenomenon of women in these agencies, see Jennifer Wilcox, Sharing the Burden: Women in Cryptology during World War II (Fort George G. Meade, MD: Center for Cryptologic History, 1998), SRH-152, “Historical Review of OP-20-G,” 1945, 3; Alvarez, 115-119.
 “German Traffic Analysis in Sixta,” NARA, RG 457, HCC, Box 1429, Folder 4729.
 “Report of Colonel McCormack’s TDY to London, May-June 1943.” NARA, RG457, HCC, Box 1119, Folder 3600, June 1943.
 William F. Friedman, “E Operations of the GC&CS at Bletchley Park,” NARA, RG 457, HCC, Box 1126, Folder 3620.
Continue to Part 5