That is simply not true, Partisan. You may repeat it to your heart's content but that does not make it any less incorrect. As I have informed you previously, there was indeed a black regiment from Richmond that was armed and engaged in combat shortly before the better known battle of Sailor's Creek. It is a few miles away from that site and, if you are interested, I will happily provide you with directions to go there and see it yourself. The on-site US park service markers AND Virginia markers clearly recount the event citing original documents.
Propagators of the silly neo-Confederate myth about black rebel troops, even some government employees in times past, have had incentives to place erroneous markers around, which when false prove nothing.
If you have any evidence whatsoever that the markers there are false, please present it. I am inclined to believe that they are not for several reasons. First, they are new displays (probably less than 10 years old) that are part of the US govt's "civil war heritage trails" system. Second, they quote an account of the battle on them. Third, they depict a sketch from the time of the battle showing the soldiers fighting. Fourth, the reference to the blacks is specific and details rather than a passing "oh, by the way, the confederates who fought here were black." And fifth, an 1865 news account out of nearby Farmville, VA just before the battle reports seeing a regiment of newly raised black confederates taking a defensive position outside of town. This all suggests that the markers are indeed credible and, absent of any specific reason as to why the markers would not be credible, it is an absurd and unsupportable conclusion to assert what you do.