The Bletchley Park Codebreakers Read Online Free Page A

class when it came to Sigint. Despite a general awareness of the importance of wartime intelligence and a particular fascination with espionage, dating back to his experience of naval intelligence in the First World War, Roosevelt failed to grasp the importance of Sigint. Though Magic provided by far the best guide to Japanese policy during the year before Pearl Harbor, he showed only a limited interest in it. As well as sanctioning the absurd odd-even date division of labour between naval and military cryptanalysts, he also agreed to a further bizarre arrangement by which his naval and military aides took turns in supplying him with Magic in alternate months. This arrangement led to predictable confusion, including the suspension of the Magicsupply in July 1941, after FDR’s military aide breached Sigint security by absentmindedly leaving Japanese decrypts in his wastepaper basket. Not until November did the President finally lose patience and insist that Magic henceforth be communicated to him exclusively through his naval aide, Captain John R. Beardall. When shown Japanese decrypts, Roosevelt very rarely commented on them. Not until three days before Pearl Harbor did he discuss with Beardall the significance of any of the Magic revelations.
    Churchill would never have tolerated the confusion allowed by Roosevelt in both the production and the distribution of Magic. He also showed far greater appreciation both of his cryptanalysts and the intelligence which they produced. Captain Malcolm Kennedy, one of the leading Japanese experts at Bletchley Park, wrote in his diary on 6 December 1941:
    … The All Highest (… Churchill) is all over himself at the moment for latest information and indications re Japan’s intentions and rings up at all hours of the day and night, except for the 4 hours in each 24 (2 to 6 a.m.) when he sleeps. For a man of his age, he has the most amazing vitality.
    It would never have occurred to Roosevelt to ring up his cryptanalysts for the latest news. (Had he done so on 6 December, he would have discovered the confusion in the decryption of the fourteen-part Japanese telegram caused by the odd-even day arrangement.) Churchill also showed far greater determination than Roosevelt to ensure that his cryptanalysts had adequate resources. The American intelligence failure to provide advance warning of the Japanese attack on Pearl Harbor was due primarily to the difficulties in reading the latest variant of the main Japanese naval code, JN-25B. Though Magic contained no clear indication of plans for the surprise attack, undecrypted naval messages did. ‘If the Japanese navy messages had enjoyed a higher priority and [had been] assigned more analytic resources,’ writes the official historian of the NSA (the current US Sigint agency), Frederick Parker, ‘could the U. S. Navy have predicted the Japanese attack on Pearl Harbor? Most emphatically yes!’ JN-25B was not read to any great extent before Pearl Harbor because only a total of between two and five cryptanalysts had ever been assigned to work on it. The success in breaking Japanese naval codes, whenthe number of cryptanalysts was increased after Pearl Harbor, was a crucial element in the US victory at Midway only six months later.
    In the months before Pearl Harbor, when OP-20-G lacked the resources required to read JN-25B more fully, it did not occur to American naval cryptanalysts to appeal directly to Roosevelt. At exactly the same time, faced with a less critical though still serious shortage of resources, Bletchley Park’s leading cryptanalysts appealed directly to Churchill. The most junior of them, Stuart Milner-Barry, delivered the message personally to Number 10. Churchill’s response was immediate: ‘ACTION THIS DAY. Make sure they have all they want on extreme priority and report to me that this has been done.’

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THE GOVERNMENT CODE AND CYPHER SCHOOL AND THE FIRST COLD WAR
    MICHAEL SMITH
Introduction
    Our view of espionage is now