Perhaps Bletchley Park's greatest success was still to come with the breaking of the Germans' strategic ciphers. These complex ciphers were used to secure communications between Hitler in Berlin and his army commanders in the field. The intelligence value of breaking into these was immense. Initial efforts were manual and successful, but could not keep up with the volume of intercepts. Under Professor Max Newman the ‘Newmanry’ started to devise machines to mechanise the process. This ultimately led to the design and construction by the brilliant General Post Office (GPO) engineer Tommy Flowers of ‘Colossus’, the world's first semi-programmable electronic computer. Breaking into these ciphers allowed the Allied staff planning for the invasion of Europe to obtain unprecedented detail of the German defences.
The Codebreakers made a vital contribution to D-Day in other ways. The breaking of the ciphers of the German Secret Intelligence Service allowed the British to confuse Hitler over where the Allies were to land. His decision to divert troops away from the Normandy beaches undoubtedly ensured the invasion's success. But even as the Allied troops waded ashore, a new threat was looming and attention was being given to the role of the Codebreakers in the post-war era.