Walter - Getting PoWs to work on sensitive installations such as railways has always struck me as a brave thing to do. Was there any sabotage that you were aware of?
I am struck by the CIA's Simple Sabotage Field Manual (for, effectively, forced labourers in WW2), a copy of which popped up on an email the other day.
https://www.cia.gov/news-information...abotage_sm.pdf