Y service
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The "Y" service was a network of British signals intelligence collection sites, the Y-stations. The service was established during the First World War and used again during the Second World War. The s
Arkley View, 1943
Room 40
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Room 40, also known as 40 O.B., was the cryptanalysis section of the British Admiralty during the First World War.
Room 40 was on the first floor of the main wing of The Admiralty's Old Building, now known as the Ripley Building (built 1726) in Whitehall. It was on the same corridor as the old Board Room.
SMS Magdeburg aground off Odensholm
Zimmermann telegram as decoded by Room 40