If they were stamped and given to prisoners it wouldn't have been civil war prisoners. That coin received a lot of wear before it was stamped so it was probably stamped around 1880 at the earliest.
It is possible that it could have been used in a prison so that the prisoners would only have readily recognizable money should they escape, but typically that was handled through the use of tokens or scrip. That way in the case of an scape they would not have any kind of money with even a remote chance of being accepted.
It is possible that it could have been used in a prison so that the prisoners would only have readily recognizable money should they escape, but typically that was handled through the use of tokens or scrip. That way in the case of an scape they would not have any kind of money with even a remote chance of being accepted.


















