“In 1864, black Union troops were involved in operations against Lee's army outside Richmond and Petersburg, and some of them are taken prisoner. Lee puts them to work on Confederate entrenchments that are in Union free-fire zones. When Grant gets wind of this, he threatens to put Confederate prisoners to work on Union entrenchments under Confederate fire unless Lee pulls out. So Grant was willing to embrace an eye-for-an-eye, tooth-for-a-tooth retaliation policy based upon Confederate treatment of black prisoners. For Grant, it was the color of the uniform, not the skin, that mattered.”