BLETCHLEY PARK PLAYED A KEY ROLE IN THE NORMANDY CAMPAIGN, AND CRACKING THE NAZI CODES WAS ONLY THE START...

On 6 June 1944, the Allies launched the largest amphibious operation the world had ever seen and invaded Nazi-occupied Western Europe. Within a week, the Normandy coast was in Allied hands, and the chances of the Germans pushing the enemy back into the sea were fading fast. The Germans, taken by surprise, were ill-prepared, but Allied commanders knew exactly the threat they faced and how to defeat it. Much of that knowledge came from one place: Bletchley Park.

David Kenyon here sheds new light on the work of Bletchley, focusing on a less familiar part of the intelligence story: signals intelligence (SIGINT). SIGINT involved the interception of enemy wireless or radio transmissions and, as most areas of enemy activity required communication, this interception and subsequent analysis helped Bletchley's staff to expose the workings of almost all areas of German operations.

Drawing on unclassified documents, recent scholarship and the archives of Bletchley Park itself, Kenyon explores how information extracted from enemy signals traffic was collated and, crucially, the effect it had on the conduct of the war. By integrating its own information with that from other sources, Bletchley was able to supply Allied commanders with vital knowledge – precisely when they most needed it.