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It was formed shortly after the start of the war in October 1914, as a result of codebooks and maps (containing coded squares) passed on to the Admiralty by the Russians who had seized them from the German cruiser Magdeburg when it had run aground. Two copies of the three which the warship had been carrying were recovered; one was retained by the Russians and the other passed to the British.
Room 40 retained its informal name while it expanded during the war and moved into other offices. It closed in February 1919. It is estimated that Room 40 decrypted around 15,000 German communications. It was provided with copies of all interceptable communications traffic, including wireless and telegraph traffic. For the whole of its existence it was under the command of Captain (later Admiral) William 'Blinker' Hall . It was managed until 1917 by James Alfred Ewing.
It played a key role in several naval engagements during the war, notably in detecting major German sorties into the North Sea that led to the the battles of Dogger Bank and Jutland as the Briish fleet was sent out to intercept them. However probably its most important contribution was in decoding the Zimmermann Telegram, a cable from the German Foreign Office to its ambassador in MexicoThis article is about the country Mexico. For other meanings, see Mexico (disambiguation The United Mexican States or Mexico ( Spanish: Estados Unidos Mexicanos or Mexico regarding the use of the variant spelling Mejico see section The name below) is a co.
Nigel de Gray and other cryptanalysts discovered German Foreign Minister Arthur ZimmermannArthur Zimmermann ( October 5, 1864 ? June 6, 1940) was Germany's Secretary of State for Foreign Affairs from November 22, 1916, until his resignation on August 6, 1917. His name is associated with the Zimmermann Telegram during World War I. However, he w making an offer to Mexico of US territory as an enticement to join the war as a German ally. The cable was passed to the US by RN Captain Hall (the then director of Room 40), a scheme was devised to conceal how the plaintextIn cryptography, plaintext (occasionally, cleartext though there are differences) is information used as input to an encryption algorithm. This could be, for example, a diplomatic message, a bank transaction, an email, a diary — any information that someo had become available, and further to explain how the US had gotten possession of it and the cable/telegram was made public by the US. Shortly thereafter, the US entered the War on the Allied side.In 1919 it was run down and merged with the British army's intelligence unit MI1b to form the Government Code and Cypher School (GCCS), later housed at Bletchley ParkBletchley Park BP was the site of a secret British military intelligence operation during and just before World War II (WWII). The site was named after the mansion in the grounds of which it was established. While the mansion was part of the operation, ma during World War IIWorld War II was the most extensive and costly armed conflict in the history of the world, involving the great majority of the world's nations, being fought simultaneously in several major theatres, and costing tens of millions of lives. The war was fough and subsequently renamed Government Communications Headquarters (GCHQ) and relocated to Cheltenham.