The Bletchley Park Codebreakers Read Online Free

naval codebreakers sought to prevent the Army from monopolizing Magic (Japanese diplomatic decrypts). After lengthy negotiations, an absurd bureaucratic compromise was agreed, allowing the military Signal Intelligence Service (SIS) to produce Magic on even dates, and its naval counterpart, OP-20-G, to do so on odd dates. This bizarre arrangement continued to cause confusion until the very eve of Pearl Harbor. On the morning of Saturday 6 December, a naval listening post near Seattle successfully intercepted thirteen parts of a fourteen-part message from Tokyo to the Japanese embassy in Washington, rejecting US terms for a resolution of the crisis and making clear that there was no longer any prospect of a peaceful settlement. (The fourteenth part was intercepted on the following day.) This critically important intercept was forwarded by teleprinter to the Navy Department in Washington. But since 6 December was an even date, the Navy Department was obliged to forward the message to the military SIS for decryption shortly after midday. SIS, however, found itself in a deeply embarrassing position since its civilian translators and other staff, as usual on a Saturday, had left at midday and there was no provision for overtime. Doubtless to its immense chagrin, SIS was thus forced to return the intercept to the Navy. While OP-20-G began the decryption, SIS spent the afternoon gaining permission for its first Saturday evening civilian shift. By the time the shift started, however, it was too late for SIS to reclaim the partly decrypted intercept from OP-20-G. And so, for the first time, on the eve of Pearl Harbor, the rival agencies produced Magic together. SIS was able to decrypt two of the thirteen parts of the intercepted Japanese message, though the typing was done by the Navy. The Sigint confusion in Washington, at one of the most critical moments in American history, highlights the immense importance of the successful resolution of interservice rivalry by GC&CS two decades earlier.
    Equally essential to Bletchley Park’s success was Churchill’s passion for Sigint. By a remarkable – and fortunate – coincidence, Churchillbecame war leader shortly after the first Enigma decrypts, one of the most valuable intelligence sources in British history, began to come onstream. Churchill’s passion for Ultra was equalled only by his determination to put it to good use. On the tenth anniversary in 1924 of the founding of Room 40, he had described Sigint as more important to the making of foreign and defence policy than ‘any other source of knowledge at the disposal of the state’. He was also well aware that, despite some successes during the First World War, the advantage gained by breaking German codes had sometimes been wasted. The indecisive battle of Jutland in 1916, the greatest naval battle of the war, might well have ended in a decisive British victory if the Sigint provided by Room 40 had been properly used by the Admiralty. Churchill’s own use of Ultra during the Second World War was, of course, far from infallible. The exaggerated sense of Rommel’s weakness in North Africa which he derived from his over-optimistic interpretation of Enigma decrypts, for example, made him too quick to urge both Wavell and Auchinleck to go on the offensive.
    Even when due account is taken of Churchill’s limitations, however, he still remains head and shoulders above any other contemporary war leader or any previous British statesman in his grasp of Sigint’s value. That grasp depended on an experience of Sigint which went back to the founding of Room 40 early in the First World War and on his ability to learn from his mistakes in the handling of it. Had Churchill come to power in May 1940 without previous experience of Sigint, Bletchley Park might well have found his untutored enthusiasm for Ultra a dubious asset.
    Great war leader though he was in most other respects, President Franklin D. Roosevelt was simply not in Churchill’s