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Allied intelligence knew of the existence of signal intelligence agencies of the German Foreign Ministry, the Army, Navy and Air Force, and that of the Supreme Command of the German Armed Forces, the Oberkommando der Wehrmacht Chiffrierabteilung (abbreviated OKW/Chi). However, little was known of its structure, operations, or successes. Assuming that OKW/Chi was similar to Bletchley Park, a centralized agency directing focused attacks on strategic communications, and coordinating and directing the signal intelligence work of all the German armed services, therefore employing the ablest cryptanalysts, OKW/Chi was the first priority among TICOM targets.
OKW/Chi was not as it seemed to the allies. Although OKW/Chi was the highest agency in the military hierarchy, its power to coordinate and set policy for the rest of the military SIGINT organizations was limited, and mainly focused on cryptology, that is the creation of the German’s own secure communications systems. As far as cryptanalysts was concerned, OKW/Chi acted as a troubleshooter, providing high-level assistance for those systems that were unsolvable by the individual services themselves.
The roots of the OKW/Chi lie in the post WWI cipher section of the Defense Ministry created in 1920 and staffed by cryptologic veterans of that war. This predecessor to OKW/Chi, the Cipher Bureau, had a strong interest in diplomatic communications. The conditions of post WWI Europe resulted in a lack of foreign military communications, so Chief Cryptanalyst Wilhelm Fenner believed that access to diplomatic traffic would provide the practice necessary to build the staff’s skills and increase the influence of his bureau. The Cipher Bureau competed with the Foreign Ministry for access to diplomatic cables passed by the Post Office, successfully arguing that diplomatic communications would also contain information relevant to military matters. With the rise of the Nazis and the formation of the Wehrmacht as the Armed Forces Supreme Command, this unit grew. By 1937 the OKW/Chi had 40 employees, growing to almost 200 by the outbreak of the war, and by 1944 its central organization had an establishment of 800 personnel. By this time, its emphasis had shifted to the strategic with an emphasis on diplomatic and broadcasting traffic.
The strongest influence on the development of OKW/Chi was Wilhelm Fenner. Fenner was a German raised and educated in St. Petersburg, Russia where his father was the managing editor of a German language newspaper. He returned to Germany in 1909 to study at the Berlin Royal Institute of Technology, but was drafted into the Army when the First World War started. He served in Russia, France, and Serbia and eventually joined the staff of the Tenth Army, serving as an intelligence officer. After drifting through some jobs in journalism in the immediate post war era, Fenner met an expatriate Russian, Professor Peter Novopaschenny who had served in the Tsarist navy as a cryptanalyst and mentored Fenner in these black arts. Through Fenner’s contacts, they were hired as part time Russian specialists in the Defense Ministry’s cipher bureau in the autumn of 1922. The following year they were promoted to full time and Fenner was made chief of the cryptanalysis section. Fenner professionalized the service, creating a training program and developed the staff during the lean years of the depression. He also worked to maneuver his bureau into a more visible position within the government.  The conditions of post WWI Europe resulted in a lack of foreign military communications, so Fenner believed that access to diplomatic traffic would provide the practice necessary to build the staff’s skills and increase their influence. The Cipher Bureau competed with the Foreign Ministry for access to diplomatic cables passed by the Post Office, successfully arguing that diplomatic communications would also contain information relevant to military matters. With the rise of the Nazis and the formation of the Wehrmacht as the Armed Forces Supreme Command, this unit grew. By 1937 the OKW/Chi had 40 employees, growing to almost 200 by the outbreak of the war, and by 1944 its central organization had an establishment of 800 personnel. By this time, its emphasis had shifted to the strategic with an emphasis on diplomatic and broadcasting traffic.
OKW/Chi was organized into four principal groups concerned with liaison, cryptanalysis and translation, interception, and intelligence. The cryptanalytic section was composed mainly of linguists but also had a dedicated mathematical section that was set up in 1937 under the direction of Dr. Erich Huettenhain, which concentrated on the more challenging ciphers. The interception group controlled the agency’s main station at Ludwigsfelds and a number of substations and was primarily concerned with monitoring foreign new broadcast and news services, and preparing a daily foreign news summary. In addition, it also controlled a second intercept system concentrating on encrypted diplomatic Morse networks, with two large intercept stations at Treuenbrietzen and Lauf. OKW/Chi also received intercepts from the other German SIGINT organizations, and received additional raw traffic from Germany’s allies. The intelligence section was responsible for evaluating and distributing broken and translated messages, and controlled the agency’s archives.
In terms of cryptanalysts, the agency did achieve a series of minor success and was able to keep a steady flow of intelligence to the high command. They maintained a large section, up to 40 to 50 persons, dedicated to attacking Anglo-American communications. OKW/Chi made breaks into the diplomatic American strip system and possibly some military attaché M-209 traffic. They had a role in the effort to read the American military attaché in Cairo’s system that was vital to Rommel’s campaign. Other US diplomatic systems were attacked, including a five-letter system, and an unenciphered codebook of about 100,000 groups was read. There was successful work done against the British Interdepartmental Cipher; however, no high-level American or British machine ciphers were attacked successfully and OKW/Chi soon gave up its attempts. The Russian section of OKW/Chi was small and seems to have accomplished little.
Initially, OKW/Chi was primarily an agency for gathering intelligence, and its development and control of secure cryptologic systems was limited to the military and a few minor government agencies. Towards the end of the war, there was a shift in emphasis away from intelligence and towards cipher security, as represented in the November 1944 reorganization of OKW/Chi into a cryptology division and a cryptanalysis division. However, they never achieved a strong centralized authority over cipher security and they had little influence outside the military. This must have been a contributing factor to the insecurity of many German systems, including the ENIGMA.
Most of the leadership of OKW/Chi was captured at Flensburg in May 1945 and were interrogated by TICOM team 6:
Colonel Hugo Kettler, who had commanded OKW/Chi since the summer of 1943, ‘impressed his interrogators as ‘an alert, intelligent officer’, who was willing to cooperate. However, Kettler was primarily an administrator who had little knowledge of the technical aspects of his command’s cryptologic activities. Nevertheless, he gave TICOM the tip that the archives of OKW/Chi had been evacuated to the Schliersee, a mountainous lake south of Munich.
Lieutenant Colonel Metting was a regular signals officer who had worked his way up to hold a number of important posts in command of intercept and cryptologic units. From November 1941 to June 1943, he commanded the Army’s cryptologic center, Inspectorate 7/VI. He then commanded a signal battalion on the Eastern front for a few months until assigned as the second in command at OKW/Chi in December 1943. Metting, primarily an administrator, was well positioned to explain OKW/Chi’s charter, organization, personnel strengths, chain of command and liaison with other agencies. His knowledge appeared to be more extensive than Kettler’s and he was valued enough to be later transported to England for more in-depth interrogations.
Specialist Dr. Erich Huettenhain was a mathematician hired by OKW/Chi in 1937 to build up a research section that investigated the most difficult enemy systems that were beyond the capacity of the regular cryptanalysis section, and to investigate the security of the German’s own systems. As a working cryptanalyst, he provided detailed technical knowledge of the work of OKW/Chi, and at this point provided the most useful information for the TICOM investigators. He and his assistant Dr. Walther Fricke were considered such high value prisoners that they too were evacuated to England on 30 June. After the war, Huettenhain became the chief of cryptanalyst for the Gehlen Organization.
OKW/Chi began to disintegrate at the end of the war. Sections moved out of Berlin by March 1945 to the Army Signal School at Halle, while the Agency’s archives moved to Lauf. By April, most of the agency’s personnel began to move toward south Germany, breaking up into different transport trains, with most of them ultimately ending up at Werfen, near Salzburg, where they were captured by American troops. Some of the leadership of the agency went north to join the remnants of the German government near Flensburg, where the British arrested them.
When Kettler, Metting and Huettenhain went north, Wilhelm Fenner, Chief Cryptanalyst, led the remnants of OKW/Chi into Austria. On 23 April 1945, OKW/Chi officially dissolved and its personnel were incorporated into the southern branch of the Army’s GdNA. In anticipation of the arrival of the American Army, remaining materials were burnt or thrown into a river. After the surrender on 8 May, all remaining personnel were released. The Germans officially discharged Fenner from government service on 19 June with only a letter of recommendation. He then made his way back to Landshut, Bavaria and found a job as an auto and bicycle mechanic in nearby Straubing. He lived quietly there until being picked up by occupation authorities and held as a witness for the Nuremberg trials in July of 1946. From September to December, while being held at Haus Alaska, a building on the grounds of the 7707th European Command Intelligence Center at Obersrsel he was interrogated. Reports based upon his information continued to be issued by the ASA until late as 1950.
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II. The Targets >
OKW/Chi (High Command)
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