You may find the following texts of some use;
T.W.Higginson, "Army Life in a Black Regiment"
D.T.Cornish, "The Sable Arm"
B.C.Nalty, "Strength for the fight, A History of Black Americans in
the Military"
B.C. Nalty & M.S.McGregor(eds), "Blacks in the Military -Essential
Documents"
The Journal of Civil War History has contained numerous relevant
articles, see, for example,
C.W.H. 14, 1968,
R.H. Abbott, "Massachusetts and the recruitment of Southern Negroes
1863-65"
C.W.H. 35, 1989,
A.J.Bailey, "A Texas Cavalry Raid: Reaction to Black Soldiers and
Contrabands"
Hope this is of some use/interest.
Gervase Phillips,
Department of English & History,
The Manchester Metropolitan University,
E-Mail: G.Phillips@UK.AC.MMU