In episode one of a major two-part series for BBC1, historian Dan Snow examines how two years of meticulous planning, espionage and the analysis of millions of three dimensional aerial photographs helped the Allied Forces gain a foothold in Northern France.

The concluding part of historian Dan Snow's major two-part series, tells the powerful and heroic stories of those who risked their lives on the beaches of Normandy, to save the world from Nazi Germany.