The issue of prisoners taken during war goes back many centuries. Depending on the nature of theconflict prisoners were either) regarded as booty/slaves belonging to the conqueror, ii) hostages to be heldfor ransom or exchange, or iii) slaughtered outright.
It is probably true to say that the American Civil War, as the first modern war, marked a change in howprisoners were regarded and treated. The early stages of the Civil War reflected more modern thinking onthe status of prisoners of war; individual soldiers were enemies only so long as they were armed and thecaptor’s only rights over prisoners were to keep them from returning to the battle lines. This resultedinitially in more humane treatment for those officially classified as prisoners of war. A system of parolesand exchanges was used where prisoners were released (“paroled”) to their homes after signing adocument declaring that they would not raise arms until a formal exchange occurred - whereby the twosides met on the battlefield and exchanged men of equal rank.