An Interesting Question

I came across this query, posed by a professionally-trained (and PhD-bearing) historian who hails from the South:

Why in 1865 when the US had crushed the rebs, didn’t the Republicans establish equality for blacks on a firm legal foundation?

Apparently this professional historian’s training was rather incomplete, unless we are simply to assume that the scholar in question is asking a question to provoke discussion because he in fact knows the answer.  Or does he?