In the case of the books you cite, southern partisans whose agenda is to redeem the moral stain that adheres to the confederate cause by digging up random bits and holding them up to say, "See, it really wasn't about slavery! Look, here's a black guy who got a confederate pension!"
I was talking about the mainstream history books, many of which were written by flaming liberals, which you have obviously been reading. Sad you don’t want to read other books with historical accounts that challenge your belief system.