Why slavery in America against blacks is the worst slavery in modern history.
Did you not know that blacks in America feel no genealogical connection to blacks in Africa? That connection was dissolved as soon as slavery set foot on North American soil. There is no family tree that points blacks in America to a village in Congo or Ghana, or Morocco. Not like an Asian person can trace their facility tree straight to Korea or Thailand.
And that is what makes American slavery the worst slavery known to man. Never in the worlds history have people been completely removed from their families, bred for profit like livestock and not because of a different religion or a war with an enemy but because they are of a different skin tone.
No doubt the Holocaust was ugly but you are not talking about 400 years of completely stripping a person of his humanity until he believes that he is not a man at all.