'A shadowy entity': M.I.1(b) and British Communications Intelligence, 1914–1922*. Issue 3 (16th April 2017) - Bruce, James
Abstract: Although the part played by the British War Office's cryptanalytic bureau in diplomatic cryptanalysis during the First World War is better understood than formerly, its contribution to military Communications Intelligence (Comint) has remained largely unknown. This article describes the origins of what eventually became M.I.1(b), its wartime development as a military cryptanalytic (and eventually cryptologic) bureau, and its post-war demise; it also seeks to identify the factors that contributed to its subsequent obscurity. It concludes that M.I.1(b) played a key role in British army Comint during the First World War, both through its own cryptanalytic work and in supporting and coordinating the efforts of widely dispersed field cryptanalytic activities, and that its subsequent obscurity has served to distort understanding of the development of British Comint.