Did free slaves fight for the Confederacy in the war?

It is uncertain to tell if any were actually part of the Confederacy in battle, but I highly doubt it. Most slaves were considered to be inferior and were forced to stay on the farms. If a slave was to fight it would probably be for the north. I only know of one actual group of slaves that fought in the war. (There were a couple hundred in the group) and people were racist towards them, and they were also kept out of battles.