Most history of southern heritage speaks of contributions made by white southerners of the 1800s during and shortly after the civil war. Not so much is spoken of contributions made by blacks for that time period. A greater treatment on the subject matter of black southerners can be found in studies that cover the Reconstruction era.
After slavery was officially abolished, newly freed black men entered into politics and joined the Republican Party. Most white southern men who were Confederate veterans were Democrats at that time. Even though some black southern men who joined the Republican Party during Reconstruction did contribute to the Confederacy (voluntarily or otherwise), there was still some racial bitterness towards them, as the black republicans ushered in Civil Rights which was opposed by most white Democrats.
There’s a book entitled “Black Americans In Congress 1870 -2007″ that reportedly has information on every black American who served in Congress from 1870 (which was the year that the 1st black American took office in Congress). My review of this book is pending.