"...
what could Lincoln have done that would have changed your view of him?"In short? Recognized the error of his ways and let the South go free! Error is no excuse!
"So wide his erudition's mighty span, he knew creation's origin and plan, and only came by accident to grief, he thought, poor man, 'twas right to be a thief."
Ambrose Bierce
But in Lincoln's view he wasn't in error, the south was. That view is shared by a great many other people. It seems that the only way Lincoln could have redeemed himself in your eyes was to do the one thing that he believed was wrong. Had he done that the south would no doubt still be blaming him for all their problems to this very day.