To which 12.5 million do you refer? If you mean all the Africans brought to the Western Hemisphere, how much part did whites here have in that when fully half of these Africans went to Brazil and most of the remainder went to the West Indies colonies of various nations, leaving only 400,000 that were brought to the North American mainland? That makes no sense. Although some Yankee families got rich trading slaves to the West Indies for New England rum.

On the other hand, if you mean the Africans who, once here, lived, labored and suffered through slavery, Jim Crow and so forth, then that adds up; at least it can add up. I'd be obliged if you would specify these things and also let me know what your sources are.

The whites also simply opened a new direction for an already (and still today) existing slave trade: the Arab trans-Sahara slave trade. If you want to see a horror, read John Azumah Adembillah's The Legacy of Arab Islam in Africa. This slave trade is probably still going on under the law's radar and, over fourteen centuries, has brought 18 million Africans to the slave markets of Algiers, Cairo and, yes, Mecca as well--and has left the bones of 120 million in the Sahara sands!

I hope I'm pretty much on your side inasmuch as tu quoque is NOT my point. My point is, be specific whereof you speak, be ready with sources for your facts and figures and try to avoid hyperbole. That way you gain much more cred (especially with doughfaces who would rather die than openly acknowledge it) than with raging hyperbole. Save the latter for in-house exhortations.