Understandable but it wasn't like the North was super united during the War,Lincoln wasn't in a position w/ a war weary nation to keep turning up the heat,being the common sense person that he was he immediately recognized the cards he held and chose healing knowing it had its flaws and was the lesser of 2 evils. Grant faced a high level of pushback and sent Union forces to quell the KKK w/limited success, it was so prevalent that it was a game of whack a mole, I mean look at today 160 yrs. later,the south is still stacked w/stars+bars waving rednecks as a reminder of the dark forces confronted by Lincoln and then Grant ccgunsYou had both a cold civil war and a successful terrorism campaign with the KKK for well over a hundred years.
“You were given the choice between war and dishonour. You chose dishonour, and you will have war.' - To Neville Chamberlain”
― Winston Churchill
Compromising your principals for peace is always a bad idea, especially when dealing with the dishonest and dishonorable, though necessary at times.