Hi
An interesting article summing up quite succinctly I think what Ford was all about. There is a point that a director make a film from a script scripted from a story and therefore is constrained to a certain extent with the material that he is given.
In an article that I wrote for the Big Trail and which I later included on one of our sites, I argued that John Wayne was not a cold blooded killer in western films killing thousands of Indians.
That instead the reverse was the case and the number very small, in fact in one film She Wore A Yellow Ribbon in the entire film he never drew his gun let alone fire it.
As for the Birth of a Nation Ford was a fledgling actor and probably did as he was told.
His attempts to make sure that the Navajos were employed and paid quite well whenever he shot in Monument Valley showed a lack of racism.
Regards
Arthur