C. G. McKay, Bengt Beckman. Swedish Signal Intelligence, 1900-1945. London: Frank Cass Publishers, 2003. xvii + 310 pp. $114.95 (cloth), ISBN 978-0-7146-5211-5.

Reviewed by Ernie Teagarden (Emeritus, College of Business and Information Systems, Dakota State University)
Published on H-Diplo (February, 2005)

Swedes Give Bletchley Park Some Competition

C. G. McKay, a military intelligence specialist, and Benet Beckman, a former official with the Swedish National Defence Radio Establishment, have written a fine account of the development of Swedish signals intelligence from 1900 to the conclusion of the Second World War. Now commonly referred to by the acronym, SIGINT, signals intelligence covers such areas as radio direction finding and monitoring, enciphering and deciphering of messages originally in plain text, techniques of wired and wireless message transmission, and the usages and management of diplomatic and military information gained through electronic interception.

This book could easily serve as the textbook for any Swedish signals intelligence course taught in English. Such courses are hard to find so it may have a better future as a supplemental text or as a primer for the reading public. Some historians do not feel friendly toward subjects which include mathematics and logic in their content and this feeling might deter their use of this book as a supplemental text for a modern history course. On the other hand, faculty who teach electronic signals and/or cryptanalysis courses, or interested laymen who believe Bruce Schneider's Applied Cryptography is the crypto-bible, or who read Cryptologia may prefer a more technical emphasis. So, this said, what do McKay and Beckman have to say?

They write in a straightforward manner. They start their narrative with basic material like the invention of electronic devices such as telegraph, telephone, and radio, and the practicality of each for civilian and military use. The Swedish industrial structure, which gave some attention to research and development (R&D), accepted electronic innovations more readily than did most of its European neighbors. In the years preceding World War I, the Swedish Royal Navy (RN) pioneered radio signals intelligence and had successes in monitoring Russian fleet communications. Unfortunately, naval efforts and successes did not yet carry over to other areas of the Swedish establishment.

During the First World War Sweden was a "pro-German neutral." There was little pro-British sentiment in Sweden when the war began and the imposition of the Allied blockade did nothing to encourage it. Germany received the benefit from Swedish interception of Russian communication traffic throughout the war and even during the early months of the Bolshevik Revolution. The Swedish Ministry of Foreign Affairs provided its facilities to the German Foreign Office, for the transmission of its transoceanic dispatches, thus avoiding British interference and censorship. German telegrams to Washington, D.C. alone were said to have reached as many as twenty-two per day before the end of 1914. Called the "Swedish round-about" by the Allies, this operation was discovered by the efficient British "Room 40" cryptanalysts. Anglo-British complaints about the effect of this practice on Swedish neutrality were met by Swedish promises that it would be terminated. The "round-about" never really ceased during the war; instead, Swedish procrastination prevailed. Also, the British could gain some information by reading the German dispatches.

During the interwar period, Swedish signals research led to improvements in organization and technology. In 1927, Swedish intelligence concluded that Soviet fleet headquarters had intensified its interest in Swedish naval matters. Monitoring of Soviet signals traffic was resumed. By 1931 the Swedes had added several more countries to its reading list. During this same period, the Swedes took an interest in the new cryptomachines. Featured was the work of a Russian-born Swede named Boris Hagelin. His first major accomplishment was the construction in 1925 of a cipher machine (B-21) for the Swedish General Staff. Hagelin also supplied the French with an improved version (B-211) of the machine and delivered five hundred units before 1939. Much of what was accomplished in signals intelligence between wars can be attributed to the drive and energy of Capt. Erik Anderberg (RN). He supported and encouraged work leading to technical improvement in signals, including machine encryption. Anderberg was appointed head of the Signals Communications Section when the Swedish Defence Staff was organized in 1937. Regardless of Swedish successes, its cryptology staff remained small, about twenty-two trained people, most of whom were so poorly paid that they had to "moonlight" to maintain a decent living standard.

At least two incidents stirred neutral Sweden after 1939 to increase its efforts in the area of signals interception. Both must have been frightening. The Soviet Union annexed the three Baltic republics and ultimately defeated Finland in the 1939-40 Winter War. More surprising was the ease with which Germany occupied Denmark and Norway and defeated France in 1940. The authors stress these events in making the Swedes recognize that forewarned is forearmed when it comes to learning what might be Soviet and, especially, German moves on Swedish national territory and its people.

It was given to mathematics professor Arne Beurling to decipher the German messages passing over leased lines in Sweden. These messages originated from Siemens-produced cryptomachines, which the Germans called the Geheimschreiber ("secret writer") T52AB. Beurling decoded the operation of the T52AB in relatively short order and, likewise, the improved models which followed. Once Beurling understood how the T52AB functioned, he and his associates were able to construct special decryption machines.

Lines and airwaves between Germany and Norway, Sweden and Finland were intercepted. Diplomatic messages were favored, since the Swedes wanted to know German intentions. In order to better coordinate radio encryption and decryption efforts, the National Defence Radio Establishment was created in 1942 under Commander Torgil Thoren. Placed directly under the Defence Department, its duties were set forth in a royal decree dated June 30, 1942. Swedish signal intelligence accomplishments may have added mightily in keeping the country out of the war.

The authors have accomplished much with this book. They describe the impressive Swedish contributions in the field of wired and wireless communications and interceptions. In both world conflicts the British were dominant in the science of cryptanalysis. Their successes in Room 40 and at Bletchley Park are well known. The reading public, during the past twenty-five years, has read much about the unraveling of the German Enigma machine, but little has been published about Swedish developments in cryptanalysis, machine driven or otherwise. The reading public knows of Alan Turing and his decryption efforts at Bletchley Park as well as the construction of his Universal Turing Machine, a precursor to the modern computer. Now the English reading public can know something of the efforts and achievements of Arne Buerling. Had the authors compared and contrasted the work of Turing and Buerling the results might have been interesting. Both spent time at Princeton's Institute of Advanced Study. Beurling received Einstein's old office, a signal honor. Certainly Beurling's hard work did much to keep Sweden neutral and unoccupied.

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Citation: Ernie Teagarden. Review of McKay, C. G.; Beckman, Bengt, Swedish Signal Intelligence, 1900-1945. H-Diplo, H-Net Reviews. February, 2005.
URL: http://www.h-net.org/reviews/showrev.php?id=10240

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