MI1 or British ''Military Intelligence, Section 1'' was a department of the British
Directorate of Military Intelligence, part of the
War Office
The War Office was a department of the British Government responsible for the administration of the British Army between 1857 and 1964, when its functions were transferred to the new Ministry of Defence (MoD). This article contains text from ...
. It was set up during
World War I
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...
. It contained "C&C", which was responsible for code breaking.
Its subsections in World War I were:
* MI1a: Distribution of reports, intelligence records.
* MI1b: Interception and cryptanalysis.
* MI1c:
The Secret Service/SIS.
* MI1d: Communications security.
* MI1e: Wireless telegraphy.
* MI1f: Personnel and finance.
* MI1g: Security, deception and counter intelligence.
In 1919 MI1b and the Royal Navy's (NID25) "
Room 40
Room 40, also known as 40 O.B. (old building; officially part of NID25), was the cryptanalysis section of the British Admiralty during the First World War.
The group, which was formed in October 1914, began when Rear-Admiral Henry Oliver, the ...
" were closed down and merged into the inter-service Government Code and Cypher School (
GC&CS
Government Communications Headquarters, commonly known as GCHQ, is an intelligence and security organisation responsible for providing signals intelligence (SIGINT) and information assurance (IA) to the government and armed forces of the Un ...
),
[ ] which subsequently developed into the
Government Communications Headquarters
Government Communications Headquarters, commonly known as GCHQ, is an intelligence and security organisation responsible for providing signals intelligence (SIGINT) and information assurance (IA) to the government and armed forces of the Un ...
(GCHQ) at Cheltenham.
Oliver Strachey
Oliver Strachey CBE (3 November 1874 – 14 May 1960), a British civil servant in the Foreign Office, was a cryptographer from World War I to World War II.
Life and work
Strachey was a son of Sir Richard Strachey, colonial administrator and ...
was in MI1 during World War I. He transferred to
GC&CS
Government Communications Headquarters, commonly known as GCHQ, is an intelligence and security organisation responsible for providing signals intelligence (SIGINT) and information assurance (IA) to the government and armed forces of the Un ...
and served there during World War II.
John Tiltman
Brigadier John Hessell Tiltman, (25 May 1894 – 10 August 1982) was a British Army officer who worked in intelligence, often at or with the Government Code and Cypher School (GC&CS) starting in the 1920s. His intelligence work was largely conn ...
was seconded to MI1 shortly before it merged with
Room 40
Room 40, also known as 40 O.B. (old building; officially part of NID25), was the cryptanalysis section of the British Admiralty during the First World War.
The group, which was formed in October 1914, began when Rear-Admiral Henry Oliver, the ...
.
Notes
References
What happened to MI1 - MI4?* Updated and extended version of ''Action This Day: From Breaking of the Enigma Code to the Birth of the Modern Computer'' Bantam Press 2001
* Gannon, Paul, ''Inside Room 40: The Codebreakers of World War I'', Ian Allan Publishing, 2011,
{{DEFAULTSORT:Mi1
Cryptography organizations
Defunct United Kingdom intelligence agencies
1910s establishments in the United Kingdom
Military units and formations disestablished in 1919
United Kingdom in World War I
Military communications of the United Kingdom