As far as I can tell the majority of U.S.C.T. regiments were made up of ex-slaves (contribands). There were very few black regiments which were made up of a majority of free blacks. In fact I don't believe there were any that fit that composition of majority of blacks who were freed prior to 1860.
The second part of the our modern day thinking problem is the premice that someone owes someone else repayment for something, or some wrong they precieve was done. If you go back in history far enough with that kind of thinking, everybody owes something to everyone else. Revenge and retribution is wrong. It doesn't make any difference if you take revenge that with the point of a bayonet, or the point of a legislators pen, it is still wrong.
So because the black union soldiers at Fort Pillow were ex-slaves does not give them the right for any such actions in my opinion. It doesn't justify anything, then or now.
I just recently found out that most of my mothers relatives who remained in Europe, when her GGGG grandfather came to America in the 1700's, were wiped out by the Nazi during WW II, because DNA test revealed that they were Germanic and Polish Jews.
How long should I demand retribution for those wrongs committed against my mother's family? Or When is the South going to recieve repayment for the reconstruction?