In our second episode of Dig WW2, Dan Snow heads out to sea to hear the story of the Empire Heritage, a cargo ship filled with Sherman Tanks sunk off Malin Head during the Battle of the Atlantic in 1944. Staying on the water, he visits an RAF Flying Boat Base on Lough Erne, where he gets to fly in an original WW2 Catalina, an aircraft built for hunting U-boats. Dan also gets to hear some of the stories which bring a personal aspect to his discoveries, visiting a group of experts intent on discovering the unknown identities of bodies of Second World War soldiers and finally bringing closure to their families all these years later.