century people. The War Between the States was still a sore subject at that time. If you were a Republican, you were considered a carpetbagger and were not welcome. Many people switched to the Republican party to get government jobs etc. as cited in the article.
Even my grandmother who died in 1977 (born 1890) hated Yankees till the day she died. She remembered how her mother told her about what the Union troops did to their farm on the way through.
So with that as a backdrop, I can understand his feeling of being railroaded. When 100k people want a pardon and you execute them anyway something is not quit right. Especially for the time period, back then if you killed someone an were not in the right they wanted you killed quick. Not like today.