Slaves fought on both sides of the
war. This
war pitted brother against brother. Some Yankees fought
for the confederacy, not because of the slavery issue, but rather the states rights issue. Some Southerners fought on the Union side. Not that they disliked slavery, they wanted to force the South back into the Union.
Both sides had unbelievably atrocious POW camps. But it seems only the Confederate ones get the attention today.