Live from Post-Civil War: In some ways, the "good" Robert E. Lee https://twitter.com/de1ong/status/897899627252285440 was a con game the post-Civil War North ran on the South: unlike the evil terrorist Nathan Bedford Forrest, Robert E. Lee surrendered when he lost, accepted the verdict of history, and turned to work building up the nation as head of Washington College.
Because he accepted defeat, we are willing to acknowledge that he and his army fought bravely and nobly—albeit, as Grant said, for a cause that was one of the worst that humans ever fought for, and one for which there was the least excuse. There was an implicit bargain offered: if you accept the verdict of history and work to build up America rather than undermine the Union victory, you can be an honored part of America again. If you try to reverse the verdict cough, you cannot.
But this attempt to use the "honorable" Lee to run a con game on white Southern irredentists failed in the long run, and Lee statues became ways of saying to the local African-American population: "Grant and his army are gone, but we are still here and still in control...