The First World War was a conflict like nothing the World had ever known. More than 700,000 men mobilised in the UK would die during the conflict. Roughly 250,000 of those would have no known grave. The Tomb of the Unknown Warrior became a place where all those people who were denied a grave to visit could come to remember their loved ones. November 2020 marks 100 years since this unknown soldier was laid to rest in Westminster Abbey. For the centenary Dan Snow visits the Abbey and the National Army Museum, to learn more about an untold story behind the Unknown Warrior. Featuring Justin Saddington, curator of the Unknown Warrior exhibition at the National Army Museum.