investigations, it was believed that the inhabitants of these sites lived in holes in the ground due to the discovery of dug pits from similar sites. But Bersu's identification of cereal grains and animals bones showed that these were storage pits for food, and the discovery of large postholes helped Bersu to convince British archaeologists that the inhabitants lived in a large Iron Age roundhouse that was also excavated on the site. Bersu also introduced new methods from continental Europe regarding the digging of trenches and the investigation of timber post remains that were one of the few remnants of the domestic dwellings on the site. Internment Upon the outbreak of the Second World War, Bersu and his wife were interned on the Isle of Man as "enemy aliens" with other German-born residents. Initially they were separated, with neither aware of the others location, with Maria in Rushen Camp, and Bersu in Hutchinson Internment Camp, Douglas. But in October 1940, they were reunited when interned married couples were permitted to meet at Derby Castle in Douglas. Later they were able to live together at Rushen Camp, which was Europe's only internment camp for married couples during World War II. Director of the Manx Museum, Basil Megaw immediately saw the potential of having Bersu investigate some of the Isle of Man's significant archaeological sites. Bersu's fellow archaeologists and friends such Gordon Childe and Christopher Hawkes lobbied on his behalf to allow excavations on the Island to be conducted. Bersu was allowed to continue his research with the help of other internees and his wife Maria who did much of the recording of the excavation. They excavated a number of later prehistoric and Viking‐age sites and several important discoveries were made at Chapel Hill at Balladoole, Ballanorris, Ronaldsway, and Ballacagan. At Balladoole, Bersu expected to excavate an Iron Age hill fort, but instead also discovered Mesolithic remains; a Bronze Age cist; a Christian keeill (a small chapel); a Christian burial ground, and a Viking Age boat burial. The discovery of additional human remains at Ballateare and Balladoole have been interpreted as examples of Viking ritual slave sacrifice. Most of Bersu's investigations on the Isle of Man were at locations accessible by public transports, as neither he nor any of the other internees had cars. As Bersu used fellow internees for the excavations, however despite the presence of armed guards, they were not