I recently watched Ken Burns documentary The Civil War, and it mentioned the prisoner exchange program, when Grant ended it, because of murders of black union soldiers.

I'm curious about the rationale behind such a program. Wouldn't it allow both sides to recycle soldiers in equal measure and thus prolonging an already bloody conflict? Is this unique to the american civil war or is it an common occurence in conflicts of this era?

I am ofcourse aware of the horrible conditions the prisoners where kept under, but did that particulary bother the high command of either side?