As Big Tim mentioned, the Curragh was used as a detention camp during WW2. There were 3 sections for the IRA, Allied airmen and German mariners and airman. The Germans and the Allies had a comparitavly easy time of it. They were allowed out neary every evening on parole as the war progressed. One American prisoner broke his parole and escaped to his unit in the north of Ireland. The US authorities promptly returned him to the Irish camp again! The story of the prisoners is told in a facinating book called Guests of the State.