Ah, but it would have transformed the war and the entire postwar period in ways you cannot begin to grasp, Deepthink. Kill our beloved Marse Bobby, and you'd never have had a peace, much less the era of national reconciliation that Bill Clinton has now terminated for political advantage with his "break the [Finkelstein] box" strategy to which demonization of Southern whites is key, capitalizing on and "leveraging" earlier periods of demonization in the civil-rights and00000antebellum periods and going all the way back to the 17th century, when Congregationalist ministers' pens dripped venom and ice as they described the luxurious living and dining of the prelacy-ridden Episcopalian Tidewater planters.
You'd have had to occupy, literally occupy, the South for 150 years, getting shot at the entire time. What World Wars? Your federal heavies would have been so preoccupied with "security operations" in the South, you'd have had to beg off two world wars and Korea to see to them. And you'd still have been getting shot from behind every big rock, gully, or tree. Gun control? Make me laugh.
Think about it yourself.