Secret Life of Bletchley Park - McKay Sinclair [60]
Even if they could not have known it, these young cryptographers, from the minor public schools and the grammar schools, and their peers, were set to become the dominating voices of the new age. And by 1941, the nature of the conflict was changing, intensifying further; for Bletchley, it would prove a crucial year in which Britain’s fortunes were ever more vulnerable. For all those who worked at the Park, it was a time of both exhaustion and occasionally elation.
13 1941: The Battle of the Atlantic
As the war widened and unfolded, the importance of Bletch ley Park’s work – and the concomitant pressure to get every tiny detail absolutely right – increased accordingly. In 1941, during the Battle of the Atlantic, German spies in various ports reported back to German High Command that a vast British convoy, comprising thirteen cargo boats, four tankers and ships carrying innumerable aircraft parts, was sailing off the coast of Africa. This message to Hitler was sent by radio – meaning that it was also picked up by British Signals Intelligence. It was decoded at Bletchley perhaps even before German High Command got to read it. As a result, the British convoy was alerted to the imminent German danger and was able to take evasive action.
The nightmare dangers that the Atlantic convoys faced were all too easy for those back home to imagine; the vessel ruthlessly stalked by U-boats, torpedoed, with countless crew and sometimes civilian passengers perishing in the dagger-cold ocean waters. Anxiety over the peril to supplies was matched by the ache of sympathy for the men out on those seas. So a naval victory of any sort always proved to be an effective morale booster back in Britain.
There was an important lifting of spirits at sea in March 1941 thanks in great part to Mavis Batey, who had been working with Dilly Knox in the Cottage on the Italian Enigma. Mrs Batey recalls with a smile how Knox was brilliant at getting people to look at problems from unexpected angles. ‘Dilly would ask: “Which way do the hands on a clock go round?” One might say clockwise. But Knox would reply that that would depend on whether one was the observer, or the clock.’
And this lateral approach was applied to Enigma. Mrs Batey still has the ‘rods’ that were used to work out the order of the wheels inside the machine, and the starting position of those wheels for the message being cracked. But the rods were not much use unless the person employing them had a lively intelligence; and it was deep into one September night in 1940 that Mrs Batey had first found her way into the code, by guessing that the first word of a particular message, for which they thought they had the letters PERX, was in fact PERSONALE – ‘personal’.
That gave her a start, yielding up two or three more potential letters within the message. A night’s worth of infinitely patient and extraordinarily focused work later, and Mrs Batey had identified the wheel order and the message setting. It was a brilliant feat of inspiration and perseverance.
Now, in the spring of 1941, it was this same light-touch but inspired approach that cracked a message to an Italian naval commander: ‘Today 25 March is X–3.’ As Mrs Batey says now, ‘If you get a message saying “today minus three”, then you know that something pretty big is afoot.’
It was. Subsequent, more specific messages came in. Mavis worked through shift after shift, not leaving the Cottage. And then: ‘It was eleven o’clock at night, and it was pouring with rain when I rushed, ran, absolutely tore down to take it to Intelligence, to get it across to Admiral Cunningham.’
After some work, intelligence analysts deduced from the message that the Italian fleet was planning to attack British troop convoys sailing from Alexandria to Piraeus in Greece. Admiral Cunningham was in charge of the operation