C-byrån ("C bureau") was a Swedish secret intelligence agency established in 1939, sorting under the Swedish Armed Forces. It was led by Major Carl Petersén. During World War II C-byrån organized operations in the German-occupied Norway and Operation Stella Polaris in Finland.
When World War II broke out in 1939, Sweden lacked a modern military intelligence agency. Major Carl Petersén was assigned to establish it. C-byrån was established in 1939, a few months after the outbreak of the war, after a joint campaign of the then Supreme Commander Olof Thörnell and the head of the Intelligence Department of the Defence Staff, Colonel Carlos Adlercreutz. Carl Petersén and his second in command, Helmuth Ternberg, shared responsibility for the information gathering missions between them: Petersén gathered information from the Allies, while Ternberg engaged in Finland, Germany, Hungary and Switzerland. Ternberg's primary source of information, according to himself, was the head of the German Abwehr, Wilhelm Canaris. Ternberg was a German-friendly person, but for that sake not a Nazi sympathizer, however, deeply conservative and nationalist. He was like Petersén an adventurer.
One of the first people that was linked to the agency was Gunnar Jarring, who had the responsibility to attach as many academics as possible to the agency, which began in earnest in 1942. Thede Palm was one of them, PhD and friend of future prime minister Tage Erlander from their time at Lund University. Ternberg had good contacts with Wilhelm Canaris and its local organization in Stockholm, the so-called Wagner Agency. But Ternberg also recruited one of the employees, Erika Schwarze, as a secret agent, against the Germans and only for the Swedes.
Other people linked to C-byrån was art historian Stig Roth and the artist Algot Törneman. At the end of World War II, there were 149 people listed in service at C-byrån, which was housed in the so-called Centralen in an apartment at Sibyllegatan 49 in Stockholm. In 1946 C-byrån ceased to exist and Petersén and Ternberg was forced to quit. T-kontoret (T office), headed by Thede Palm, continued C-byrån's operations.
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- Helgegren, Carl-Magnus (10 November 2013). "Operation Stella Polaris och signalspaningen" (MP3). P3 Dokumentär (in Swedish). Sveriges Radio. Retrieved 13 May 2016.
- Bratt, Peter (1998-06-21). "Svensk kupp gav nazisternas ryska koder till USA" [Swedish coup gave the Nazi's Russian codes to the US]. Dagens Nyheter (in Swedish). Retrieved 17 March 2016.
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