I had this to say about Nelson Mandela in my book Injustice and will say it again.
The empowerment of formerly oppressed people often creates a volatile situation where much can go wrong and much can go right. In those situations, there is a natural human instinct toward vengeance and retribution that must be controlled by the law. In the transition from white rule to black rule in Zimbabwe, we find a stark example of what happens when the law fails to control these instincts—legally sanctioned terror against the white minority, gangsterism, and economic collapse. We find a counter-example in South Africa, where Nelson Mandela presided over a peaceful transition from apartheid that, though imperfect, was marked by adherence to the law and full legal protections for all races.
In some American counties, as the black majority became empowered after passage of the Voting Rights Act, new political leaders emerged who sought racial payback. While they did not unleash wanton violence on the scale of Zimbabwe, the same sense of racial animus animated their cause.
I highly recommend listening to Joel Pollack on with Mark Levin talking about Mandela for some keen insight into the man.