In some .808 mods you used to be able to recruit all your prisoners (one at a time) whenever you wanted. Not terribly realistic, but real handy. In .903 mods like BOWX you can eventually have a whole army of bad-arsed troops like Dragon Guards and then need fear nothing. Great for the ego, maybe not so much for gameplay. Still a good way to get top-level enemy troops a few at a time, though you may pay the price in morale.