Alderney, like the rest of the Channel Islands, was occupied by German forces from 1940 to 1945. On Hitler's orders it was turned into a fortress, covered in concrete and steel fortifications. After liberation British forces dumped a vast amount of military hardware into a quarry which was then flooded. For 70 years it has remained there, hidden, forgotten..... Until Dan Snow joined a team of divers to uncover it. To watch our documentary about the Islands of Guernsey please head to History Hit TV. See acast.com/privacy for privacy and opt-out information.