Grant was a butcher of his own men.
Grant and Lee commanded armies for about the same amount of time - Grant actually commanded for several months longer. Yet it was Lee's Army of Northern Virginia which suffered the greater total casualties in raw numbers than armies commanded by Grant. So if Grant was a butcher then was Lee a greater one?
Lee got more of his own soldiers killed or wounded attacking Cemetery Ridge at Gettysburg then Grant got killed or wounded in the assault against the Confederates at Cold Harbor.