It's June 1944, and four Allied soldiers are writing what may be their last words to their loved ones. They face, along with 150,000 others, the most terrifying day of their lives - the invasion to liberate Europe from Nazi rule. In these letters, read by Ben Lamb, Samuel West, Seamus Morrison and Tom Rhys Harries to mark the 70th anniversary of the Normandy landings, the men provide a unique insight into what it took to go into battle. Matthew Macfadyen narrates.