Using rare archive footage and exclusive interviews, this series takes you to the heart of a war that was fought out far from the bombs and shells of any battlefront. A war that involved the brilliant skills of mathematicians and chess players. The war of the codebreakers. Twice in 50 years the ability to crack the enemy's most secret codes, and so learn the battle plans of enemy commanders in the field, proved to be the vital factor in achieving victory. Revealed here are the remarkable exploits of American and British codebreakers and their immense contribution to victory in Europe and the Pacific during WWII.