The Rebirth of a Nation: Directed by D. W. Griffith
Native American genocide - Get the white-out and presto - it never happened.
Brutality of Slavery - Gone With The Wind.
Terrorism of KKK - just some good ole boys expressing their 1st Amendment Rights.
Mexican/American War - apply the airbrush.
Yeah just like that. According to these folks, one can just pick-chose-ignore American history at one's discretion. If the portrait is disturbing just recast it to be more favorable - get rid of the inconvenient truth.