N.I.D. 25

Naval Intelligence Division, Section 25, also known as I.D. 25 was the section of the Naval Intelligence Division of the British Royal Navy responsible for monitoring and deciphering Imperial German Navy signals.

Room 40

At the outbreak of war on 4 August, 1914, a series of coded naval signals were picked up by the Admiralty's wireless station at Stockton. On 5 August the British cable ship Telconia started cutting Germany's telegraph cables, forcing her to resort to wireless telegraphy and foreign cables. Some wireless messages were picked up and recorded by the General Post Office, the Marconi Company and ham operators, which were then forwarded to the Director of Intelligence Division at the Admiralty, Captain Henry F. Oliver.

Bibliography

• Gannon, Paul (2010). Inside Room 40: The Codebreakers of World War 1. Hersham: Ian Allan Publishing. ISBN 978-0-7110-3408-2.