Oklahoma was a territory where slavery was legal. The tribes in Oklahoma fought on both sides of the conflict.
Your information seems to support somebody's agenda about blacks in the Civil War, and to be slanted, subjective, and inaccurate. I suggest that, instead of siting "a long article about the Civil War" and concluding with "for what it's worth", that you be specific about your source, and honest about your intent. If you are suggesting something along the old line of "blacks in the South were happy with their system and willing to go to war to preserve it" be honest about it. If you are suggesting that "black" families had and held black slaves and thus had an interest in supporting the Confederacy, you definitely need more specific and accurate information to support such a claim.