Personally, I don't have a problem with Mandela having decided to resort to violence, and I don't think that he did, diminishes him.
I made the point because there are many who wish to deify him who conveniently forget this aspect of his story.
By the time he was released from prison (thanks to the political and economic pressure of the West) he could have easily led black South Africans in a blood bath. The rest of the world (the West) might have uttered protests but white South Africans would still have been slaughtered.
This is hardly comparable to the situtation in which Washington found himself: Leading an army of citizens in violent struggle against a professional army of occupation; largely manned by foreign mercenaries.
In any case, it should have been obvious that my comparison between Mandela and Washington was that neither chose to exploit their opportunities and amass great personal power. That to me, is greatness.