In the history of Cryptanalysis, Room 40 also known as 40 O.B. (Old Building) (latterly NID25) was the section in the Admiralty most identified with the British cryptoanalysis effort during the First World War.
Room 40 was formed in October 1914, shortly after the start of the war. Admiral Oliver, the Director of Naval Intelligence, gave intercepts from the German radio station at Nauen, near Berlin, to Director of Naval Education Alfred Ewing, who constructed ciphers as a hobby. Ewing recruited civilians such as William Montbgomery, a translator of theological works from German, and Nigel de Grey, a publisher.
The basis of Room 40 operations evolved around a German naval codebook, the Signalbuch der Kaiserlichen Marine (SKM), and maps (containing coded squares), which had been passed on to the Admiralty by the Russians. The Russians had seized them from the German cruiser Magdeburg when it ran aground off the Estonian coast on 26 August 1914. Two of the four copies that the warship had been carrying were recovered; one was retained by the Russians and the other passed to the British.
In October, 1914, the British also obtained the Imperial German Navy’s Handelsschiffsverkehrsbuch (HVB), a codebook used by German naval warships, merchantmen, naval zeppelins and U-Boats. This had been captured from the German steamer Hobart by the Royal Australian Navy on 11 October. On 30 November a British trawler recovered a safe from the sunken German destroyer S-119, in which was found the Verkehrsbuch (VB), the code used by the Germans to communicate with naval attachés, embassies and warships overseas.
In March, 1915, the luggage of Wilhelm Wassmuss, a German agent in Persia, was captured and shipped, unopened, to London, where then-Director of Naval Intelligence Admiral Sir William Reginald Hall discovered that it contained the German Diplomatic Code Book, Code No. 13040.
The function of the program was compromised by the Admiralty's insistence upon interpreting Room 40 information in its own way. Room 40 operators were permitted to decrypt, but not to interpret the information they acquired.
The section retained "Room 40" as its informal name even though it expanded during the war and moved into other offices. It has been estimated that Room 40 decrypted around 15,000 German communications, the section being provided with copies of all intercepted communications traffic, including wireless and telegraph traffic. Until May 1917 it was directed by Alfred Ewing, and then direct control passed to Captain (later Admiral) Reginald ‘Blinker’ Hall, assisted by William Milbourne James.
Merger with Military Intelligence (MI)
In 1919, Room 40 was deactivated and its function merged with the British Army’s intelligence unit MI1b to form the Government Coder and Cypher School (GC&CS), which was housed at Bletchley Park
during the Second World War and subsequently renamed Government Communications Headquarters (GCHQ) and relocated to Cheltenham.
Room 40 was formed in October 1914, shortly after the start of the war. Admiral Oliver, the Director of Naval Intelligence, gave intercepts from the German radio station at Nauen, near Berlin, to Director of Naval Education Alfred Ewing, who constructed ciphers as a hobby. Ewing recruited civilians such as William Montbgomery, a translator of theological works from German, and Nigel de Grey, a publisher.
The basis of Room 40 operations evolved around a German naval codebook, the Signalbuch der Kaiserlichen Marine (SKM), and maps (containing coded squares), which had been passed on to the Admiralty by the Russians. The Russians had seized them from the German cruiser Magdeburg when it ran aground off the Estonian coast on 26 August 1914. Two of the four copies that the warship had been carrying were recovered; one was retained by the Russians and the other passed to the British.
In October, 1914, the British also obtained the Imperial German Navy’s Handelsschiffsverkehrsbuch (HVB), a codebook used by German naval warships, merchantmen, naval zeppelins and U-Boats. This had been captured from the German steamer Hobart by the Royal Australian Navy on 11 October. On 30 November a British trawler recovered a safe from the sunken German destroyer S-119, in which was found the Verkehrsbuch (VB), the code used by the Germans to communicate with naval attachés, embassies and warships overseas.
In March, 1915, the luggage of Wilhelm Wassmuss, a German agent in Persia, was captured and shipped, unopened, to London, where then-Director of Naval Intelligence Admiral Sir William Reginald Hall discovered that it contained the German Diplomatic Code Book, Code No. 13040.
The function of the program was compromised by the Admiralty's insistence upon interpreting Room 40 information in its own way. Room 40 operators were permitted to decrypt, but not to interpret the information they acquired.
The section retained "Room 40" as its informal name even though it expanded during the war and moved into other offices. It has been estimated that Room 40 decrypted around 15,000 German communications, the section being provided with copies of all intercepted communications traffic, including wireless and telegraph traffic. Until May 1917 it was directed by Alfred Ewing, and then direct control passed to Captain (later Admiral) Reginald ‘Blinker’ Hall, assisted by William Milbourne James.
Merger with Military Intelligence (MI)
In 1919, Room 40 was deactivated and its function merged with the British Army’s intelligence unit MI1b to form the Government Coder and Cypher School (GC&CS), which was housed at Bletchley Park
http://en.wikipedia.org/wiki/Room_40
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