2nd. LT. Chapman
Isn't Farifax county, VA in the south?
You have it nailed down and this thinking is also what caused all the trouble in reconstruction. The yankees knew very well that this was the way people in the south thought and is the very reason they installed blacks into political office in the south. They did it as an "in your face" punishment and as an offense. It set race relations, that were already bad, back at least another 50 years and caused much more violence.
There may have been another factor at Fort Pillow. It has to do with the chivalric traditions of battle and notions of social equality. This is just my wild theory, I've never read it anywhere. What's more, I've never visited the South and I really don't know what I'm talking about. So bear with me here, please.
Back in the days of yore, when some guys clanked around in tin suits, the general idea was that in battle, it should be a contest between equals. That is, equal social rank, equal weapons, equal numbers. Face to face. The code duello is the perfect illustration. No sniping, no carrying hidden weapons, no ganging up.
In battle they generally took prisoners to hold for ransom. A fund-raising activity, you might call it. So to kill a prisoner was deemed unchivalric as well as unprofitable.
Equal social rank was probably the most important of all. Aristocrats wouldn't have anything to do with common people. Noblemen wouldn't fight with yeomen. It took a thousand years to break that concept that your social status is unchangeable. What your father was, so you will be. A bankrupt aristocrat had more privileges than a wealthy merchant.
A slave society must justify itself by believing that the slaves are inferior people. And when all the slaves are black/mulatto/quadroon/octoroon, it's easy to make the transition from slaves-are-inferiors to blacks-are-inferiors. I've never read about any white slaves.
So, here you are at Ft. Pillow, a Confederate soldier facing USCTs. All your life you have been taught to believe they're your inferiors. The Yankees have changed the rules by putting them on the same level as you. The underpinnings of your life's belief about what's right and good and proper and civilized - gone! Would you feel angry, bewildered, frustrated?
I might have, in those circumstances. Rage is so hard to control.