the alderney concentration camps were built and operated by nazi germany during its world war ii occupation of the channel islands. the channel islands were the only british commonwealth soil to be occupied by the nazis. the nazis built four concentration camps on alderney island, subcamps of the neuengamme camp outside hamburg. they were named after the frisian islands: lager norderney, lager borkum, lager sylt and lager helgoland. the nazi organisation todt operated each subcamp and used forced labour to build bunkers, gun emplacements, air-raid shelters, and concrete fortifications. the camps started working in january 1942 and had a total inmate population of about 6,000.