Ultra in the Pacific : how breaking Japanese codes & cyphers affected naval operations against Japan 1941-45
John Winton (Author)
Ultra, the name given to information gained from the deciphering of messages passed by the enemy in code during the Second World War, was certainly an invaluable asset to the Allies; but its application gave rise to other problems. If the information gained was used too freely, the enemy would soon suspect that their radio traffic was being intercepted and read, and would take the necessary counter-measures
Print Book, English, 1993
Naval Institute Press, Annapolis, Md., 1993