James McPherson is concidered as an expert because his writting espouse the popular rethoric. Facts are facts, Battles are Battles, Troops movements are Troop movements, but it is the opinion of causes that makes someone an "expert" in the historical world. If you say something other than that popularist line you are considered a "Nutcase" and therefore by definition NOT an expert.

The War was about Slavery and there was no other cause. And the quicker we southerners learn that then we will become the "experts" also. Many writers have sold out their souls for the fame and reconition that comes from writting books that academia and the New York Times would praise.