Colin Powell's promotion did not just happen.
His board followed his directives and .... Colin Powell emerged on the candidate list.
As he explains in the NY Times article Colin Powell's Promotion: The Real Story "He did not get anything extra and his white colleagues did not get anything extra either. The rise of Colin Powell through the ranks of the United States Army to brigadier general had to do with his performance as a soldier”.
This is a great success story of a good diversity practice. I had heard about it a long time ago and today I mentioned it to some friends. Then I googled it and I was lucky to find this excellent article published in the NY TImes.