Alderney concentration camp
Guernsey
Lager Sylt was a Nazi concentration camp on Alderney in the British Crown Dependency in the Channel Islands. Built in 1942, along with three other labour camps by the Organisation Todt, the control of Lager Sylt changed from March 1943 to June 1944 when it was run by the Schutzstaffel - SS-Baubrigade 1 and Lager Sylt became a subcamp of the Neuengamme concentration camp (located in Hamburg, Germany).
Prison data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).