Room 40

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Room 40 ( English for room 40) was an intelligence department of the British Admiralty during the First World War . He was thus in the tradition of the "black chambers" . The code breakers from Room 40 dealt with the deciphering of secret messages from the German Reich . The code books captured by the Germans formed the basis . Her greatest success was the deciphering of the Zimmermann telegram , which made a decisive contribution to the United States' entry into the war .

In 1914, Rear Admiral Henry Oliver , director of the British Naval Intelligence Department , won over the Scottish physicist James Alfred Ewing to set up a cryptological department to decrypt the radio messages from the Nauen radio station . The Germans were forced to switch to shortwave radio for their overseas communications, as most of their overseas cables were systematically interrupted at the beginning of the war. Ewing recruited skilled cryptologists like William Montgomery and Nigel de Gray . After the department grew, it moved to Room 40 of the old Admiralty Building in November 1914 and has been called Room 40 ever since . At the time the Zimmermann telegram was deciphered, it employed around 800 radio operators and 80 cryptologists and office workers. In October 1916 Ewing left the group and the new leader was Admiral William Reginald Hall .

The most important code breaches are due to captured documents:

  • The signal book (SKM) of the cruiser SMS Magdeburg , which was stranded on the Baltic island of Osmussaare on August 26, 1914 , was captured by the Russians and a copy handed over to the British on October 13.
  • The commercial traffic book (HVB) of a German steamer confiscated in Australia at the beginning of the war reached Room 40 at the end of October.
  • In the sea ​​battle off Texel on October 17, 1914, four German torpedo boats were sunk. A British trawler found a box containing the VB for one of the boats on November 30th and forwarded it to Room 40.
  • In March 1915, the British stole the luggage of the German diplomat Wilhelm Wassmuss , which contained a diplomatic code book, in Persia .

After the end of the war, Room 40 was dissolved or merged with the MI1b department of the Directorate of Military Intelligence . This later became the Government Code and Cypher School . Some of the employees found themselves in Bletchley Park , where German Enigma messages were deciphered during World War II .

literature

  • Patrick Beesly: Room 40. British naval intelligence 1914-1918. Oxford University Press, Oxford et al. 1984, ISBN 0-19-281468-0 .
  • William James: The Eyes of the Navy. A Biographical Study of Admiral Sir Reginald Hall. Reprinted edition. Methuen & Co., London 1956.
  • Rudolph Kippenhahn : Encrypted messages. The secret script of Julius Caesar, secret scripts in World War I and II, the Pope's code book, Enigma. 4th edition. Nikol Verlagsgesellschaft, Hamburg 2006, ISBN 3-937872-37-X , pp. 60–79.
  • Gustav Kleikamp : The influence of radio reconnaissance on naval warfare in the North Sea 1914-1918. Secret! Kiel ( Reichsdruckerei ) 1934.
  • Robert K. Massie : Castles of Steel. Britain, Germany, and the winning of the Great War at sea. Random House, New York 2003, ISBN 0-679-45671-6 .
  • Barbara Tuchman : The carpenter's dispatch. Lübbe, Bergisch Gladbach 1982, ISBN 3-404-65039-5 .
  • Jonathan Reed Winkler: Information Warfare in World War I. In: The Journal of Military History 73 (2009), pp. 845-867, doi : 10.1353 / jmh.0.0324 .
  • Werner Rahn : The influence of radio reconnaissance on German naval warfare in the First and Second World War. In: Winfried Heinemann (ed.): Leadership and means of leadership (= Potsdam writings on military history. Vol. 14). Military History Research Office, Potsdam 2011, ISBN 978-3-941571-14-3 , pp. 15–56.
  • David Ramsay: "Blinker" Hall. Spymaster. The Man who Brought America into World War I. Reprinted edition. Spellmount, Stroud 2009, ISBN 978-0-7524-5398-9 .
  • Jonathan Reed Winkler: Nexus. Strategic communications and American security in World War I (= Harvard Historical Studies. Vol. 162). Harvard University Press, Cambridge MA et al. 2008, ISBN 978-0-674-02839-5 .