"Lincoln's white slaves", men conscripted to "kill or be killed", suffered the most evil form of slavery.
But, it was never really about slavery anyhow.
The nub of the problem was that the North wanted high tariffs on imported goods to protect its own manufactured products, while the South wanted low tariffs on imports and exports since it exported cotton and tobacco to Europe and imported manufactured goods in exchange. High tariffs in effect depressed the price for the South's agricultural exports; the South paid high prices for what it bought and got low prices for what it sold because of the federal tariff policy which the South was powerless to change. Southerners viewed themselves as being dominated by the mercantile interests of the North who profited from these high tariffs.