1910s establishments in the United Kingdom

MI3, the British Military Intelligence Section 3, was a division of the British Directorate of Military Intelligence, part of the War Office. It was originally set up to handle geographical information. Its subsections in 1914 included: MI3a: France, Belgium, Luxembourg, Morocco. MI3b: Austria-Hungary and Switzerland. MI3c: Germany. MI3d: The Netherlands, Norway, Sweden and Denmark. MI3e: Military translations.

MI1 or British Military Intelligence, Section 1 was a department of the British Directorate of Military Intelligence, part of the War Office. It was set up during World War I. It contained "C&C", which was responsible for code breaking.

MI2, the British Military Intelligence Section 2, was a department of the British Directorate of Military Intelligence, part of the War Office. It was originally set up to handle geographic information. MI2a handled the Americas (excluding Canada), Spain, Portugal, Italy, Liberia, Tangier, and the Balkans. MI2b handled the Ottoman Empire, Trans-Caucasus, Arabia, Sinai, Abyssinia, North Africa excluding French and Spanish possessions, Egypt, and the Sudan.