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Military Signals Intelligence (SIGINT) activities have been conducted in support of military operations since the Great War. The first dedicated capability was established by the Royal Navy just prior to WWI with collect and processing controlled by ‘ROOM 40’ at the Admiralty. Initially, focused on the deciphering of German naval traffic, it later incorporated direction finding (DF) techniques to enhance its provision of ‘Special Intelligence’ to support naval planning at the operational level. Within the first couple of years of the war, the British Army had created Special Wireless Sections (SWS) to collect SIGINT on German forces on the Western Front, later expanding operations to the Middle East and Mesopotamia. Again DF stations were introduced; developed by Captain Henry Round (Intelligence Corps), who had also been responsible for the creation of the Royal Navy’s DF chain. The SWS generated operational/theatre level intelligence reporting that was passed to their respective General HQ (and it was very much a British affair, except in Mesopotamia where Australian and New Zealanders made a significant contribution to the SIGINT effort).

During WWII, strategic military SIGINT came to the fore, pioneered by the British Government Code and Cypher School (GC&CS), ‘Bletchley Park’, and taking on many of the lessons identified by ROOM 40 during WWI. Again Special Wireless units deployed to operational theatres to conduct Electronic Support operations against enemy communication networks. These Special Wireless units were also know as ‘Y’ units and were initially most effective during the North Africa campaign. Unlike WWI, the Y units operated at two levels. Firstly they collected high-grade enciphered traffic (i.e. Engima) which was passed back to Bletchley Park where it was attacked by the cryptanalysts and then processed for dissemination back to theatre commanders via special liaison officers and not via the Y units. This was very much a case of tactical collection in support of a strategic-operational SIGINT effort, similar to modern day ‘tactical SIGINT’ operations. Secondly, the Special Wireless Sections were accompanied by Special Intelligence Sections and these were able to process and analyse communications sent in clear or in low-grade tactical codes, directly disseminating any intelligence to the tactical commander (normally corps-divisional commanders); the foundation of modern tactical Electronic Warfare (EW) operations.

Why Historical Reading Material

This reading list consists of publications that cover the historical use of and conduct of SIGINT in support of military operations for a couple of reasons. Firstly, as often quoted, "if you do not know where you came from, then you don’t know where you are, and if you don’t know where you are, then you don’t know where you are going". Although, there have been significant advances in communications and in collection technologies many of our best practices have been built on the lessons identified by our predecessors who encountered and overcome some of the fundamental challenges of EW-SIGINT operations; balancing the ‘need to know’ with ‘need to share’, secure and timely dissemination, protecting the source and the provision of actionable intelligence. Secondly, due to the secrecy surrounding this source of intelligence, there is much more material for researchers and writers relating to the historical use of SIGINT (some aspects of Bletchley Park’s operations were not released until the 1990s), giving a much more accurate interpretation of events. Lastly, it would be inappropriate to comment on the accuracy and validity of modern works, as many are not quite a true reflection of modern day operation.