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 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 Montgomery, a translator of theological works from German, and Nigel de Grey, a publisher. It was estimated that during the war Room 40 decrypted around 15,000 intercepted German communications from wireless and telegraph traffic. Most notably the section intercepted and decoded the Zimmermann Telegram, a secret diplomatic communic