Season
Season 1 Episode
Battle of the Atlantic - Season 1 Episode 2 Keeping Secrets
6.90 135 minutes In the first 18 months of war, German U-boats sank more than three million tons of shipping. Eyewitness testimony, archive film and reconstructions illuminate the story of how Allied intelligence fought back against the killers in the deep, helped by the seizure of an Enigma code machine and cipher material.
