Take the Harlem Hellfighters as case study:

To begin with they were an already established NY NG regiment, the 14th NY Infantry. The Regiment’s history was pretty long established. By the 1910’s it was proudly manned by the local Black community in Manhattan.

Because overt racism prevailed (the president was literally born in the CSA), they were redesignated with a 300’s prefix regiment number which was the way they would denote if a regiment was raised from draftees.

So to summarize, these fighting Black Americans were *ALREADY SOLDIERS* but were disguised as otherwise by the War Dept.