Thomas Dixon - A Question

I have recently been engaged in a re-read of Thomas Dixon's The Clansman - the novel that inspired D. W. Griffith's The Birth of a Nation. This book is undeniably racist. But riddle me this. Is Dixon writing with historical accuracy from  his perspective or intentionally manipulating history with an eye toward a cultural/political agenda? I've heard both sides of the argument - generally the latter. Thoughts?

With compliments,

Keith