Prisoners of war in earlier centuries, especially officers, could be given temporary or permanent freedom in return for various conditions: A parole.
This overlaps with the modern civilian use of parole for criminals. Variations including day-release; occupation or location restrictions; refraining from misdemeanors; restrictions on free association and so forth. Indeed, civilian parole has become a very popular social mechanism.
Militaries on the other hand, no longer endorse or utilise parole any more.
So when did parole of prisoners of war fall out of fashion?
Do we know why this shift occurred - considering the millennia of prior tradition?