They get mad because they truly do not and will not believe it to be true. And to what Angel on a Rag said, there were white slaves, but they were only a small minority of them. Remember not all slaves went to America they went from Cuba to Brazil. Thats the areas they touched on a triangle outlook. The only people I'd think would have a problem with the reality of the situation is white descendants of Ireland and England considering the fact they added nothing but ignorance and brutality to this country while everyone else actually put in work to make this country what made more and more people emigrate here. Seems like they were the only ones who weren't doing jack shyt when America was being built up except acting like they knew how to run a country. I always wonder though how it would be like if they lost the Rev War. Slaves probably wouldve been released earlier on a technical scale but would still do the same meager work.