Perhaps Bletchley Park's greatest success was breaking the Germans' strategic ciphers
These complex ciphers were used to secure communications between Berlin and Army commanders in the field. Messages consisted of teleprinter code encyphered with the highly complex Lorenz cypher machine. The intelligence value of breaking into these was immense. Initial efforts were successful, but were done by hand 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 large-scale electronic digital computer. Breaking into these ciphers allowed the Allied staff planning for the invasion of Europe to obtain unprecedented detail of the German defences, and to see into the minds of the enemy commanders including Hitler himself.