Again you revert to apples to oranges......So this angle of yours, that lack of charges and prosecution proves that there was no atrocity.
Would you say that every person who committed an atrocity against anyone, be it against Native Americans, or Black Americans, or whoever, has always been charged and prosecuted? If not, then that angle is meaningless in determining whether this was an atrocity.
An atrocity and a crime are not synonymous at all....there are practices today I find rather atrocious yet entirely legal in the US.....I can separate the two, in they are not the same.
In part because ones personal morals and the majority responsible for laws, are not always exactly the same.