I find it very strange the the Confederates have coloured troops and not the Union.
The US had many regiments of colored troops whereas the only coloured troops possessed by the Confederacy were the Louisiana Native Guard, who were comprised the handful of free Men of Colour that existed in Louisiana due to it's cultural differences to the rest of the south.
Now the Louisiana Native Guard more or less swapped sides when the Union took Louisiana.
Most photos of "Black Confederates" that exist were photos of camp slaves, usually posing with their masters. they'd cook and clean and carry things, but they didn't fight usually.