Assume Booth still kills Lincoln, but somehow the searchers just don’t find him, either by prior planning or luck. Or what if Booth doesn’t reveal himself and just slips away (admittedly that’s not in his personality at all). Do these change the response to the assassination?
If the assassin was not known, it would have been easier to pin the blame on a conspiracy by the defeated Confederate leadership and Johnson would have had to go along with harsher terms imposed on the Southern states. The public would demand punishment of the entire South, not just a small group of rando conspirators.
The public might “demand”, but there’s no reason that would have to have driven what either Congress or the President did. The power of popular feedback back then is not nearly what it is today.
In the counterfactual, is it more likely the government would impose harsher punishment terms on the south? Sure. Is it a sure thing? I don’t think so.
Is the OP assuming that Booth didn’t jump down from Lincoln’s booth (er…), hurting his leg and shouting out a disputed phrase? Given he was an actor in the company, a lot of people would have recognized him. Pictures of him would have circulated all over the place making it hard for him to hide for long. Plus there’s the issue with the leg injury.
There’s also the matter of his true co-conspirators who were rounded up quickly without the aid of a live Booth. The basics of the plot were then known. Nothing directly tying them to the CSA government.
I think if Booth was not seen around the shooting, his involvement in the plot would be found out. Note that Booth might have considered two options after the shooting: 1. Blending back in with the troupe. But since he couldn’t be sure he wasn’t spotted, that’s dangerous. 2. Fleeing. Leaving the scene like that would put a big red flag on him. So he pulled an Oswald.
Right, they knew who did it. If they couldn’t find him probably more people would suffer the Mudd treatment. There were still plenty of people who sided with Booth after the assassination but I don’t know if they became targets of the public or the government.
Booth’s murder of Lincoln was part of a larger plot that included killing the vice
president and Secretary of State William H. Seward. The person that was
to kill the vice president went and got drunk instead, but Seward was stabbed
numerous times with his attacker escaping. If Booth was not identified,
the capture of Seward’s attacker would cause the whole plot to be discovered and Booth’s
name would be revealed.
If Seward’s attacker and Booth managed to escape and were never
identified I guess there would have been a massive search and a
rounding up of dozens of suspicious characters. Several people would
probably unjustifiably be thrown in jail like Dr. Mudd was.