Technically speaking, wouldn't that be the correct/legal way to treat them, until the war was over?
certainly, as prior to the conclusion of the conflict and the 13th amendment et al., blacks didn't have any rights to speak of. not too many people keep in mind the fugitive slave laws which bound the North as well as the South in the antebellum period. if a slave escaped to a "free state" like Pennsylvania, and a local white individual is made aware of this, he is
compelled to participate in any pursuit and capture of the slave under threat of legal penalty. abolitionist minorities aside, most folk really did think of blacks as property. i suppose i'm just trying to combat the myth of the morally-superior yankee fighting for freedom
also, everyone remember: the first wave of seccession (south carolina, alabama, georgia, florida, mississippi) was certainly and undoubtedly brought on primarily by the slavery issue. specifically, the perceived threat of abolition of chattel slavery- a tyrant Lincoln indeed was but he was nothing like the abolitionist he was painted as throughout the south.
the second wave of seccession was brought on by Lincoln's raising of an army to, presumably, invade the south. no standing armies back then, so mustering together an army is loosely like mobilizing one's forces all along the border in modern terms. texas, arkansas, north carolina, tennessee, virginia, lousiana seceded over threat of invasion. if no northern army were mustered together, i imagine that the Deep South may well have seceded and stood alone as south carolina did for a month or two.
