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. 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.