MI5 at War 1909-1918

The years 1909-1918 can be regarded as formative for MI5, an era in which it developed from a small counterespionage bureau into an established security intelligence agency. MI5 had two main roles during this period; counterespionage, and advising the War Office on how to deal with the police and the civilian population, particularly foreign nationals in Britain.

Using hitherto neglected documents ...