@psychopathkids This looks pretty good. I need to make sure you realize that the Marshals are no longer an official arm of the Confederate States government in the timeline. They exist but have essentially become a vigilante group in the post war world. They are classified as rebels by the CSA ironically. 

My big concern is your character entering with this huge overarching purpose of assassinating the President which could be the plotline of an entire game in and of itself. The Railsplitters are not, by nature, assassins. They are focused on freeing slaves. Don't get me wrong, they'll kill if they have to, but they do not set out with this purpose generally. You have to remember that they are the descendants of the 1860-50s abolitionist movement which was dominated by religious idealsim, specifically the Quakers. Most, I think, would also argue that killing the President would in no way serve the cause. It would not topple the government and instead would incite a crackdown which would fall most heavily on slaves and make freeing them even more difficult.

All that being said, your character can of course have this goal. He just needs to be smart enough to keep it to himself. The Railsplitters are not going to welcome a gloryhound with a deathwish, especially after what happened in Philly.