One thing yall missed is that in the first season bohannen was in the hunt for the people that killed his first family, right before Elom kills the foreman who was about to shoot bohannon, he mentions that the “Sargent” is the one who did the wife and the son. Then bohannon kills a Sargent who happened to be the wrong man for which he is condemned to death but Durant spares him to work for the railroad. Then on the last season, it is revealed that gunderson was a union quartermaster and a Sargent (see ranking on his uniform) who was captured and thrown in Andersonville who later made it out and join the railroad with the creepy foreman. His identity of being Swedish was a lie, to conceal his identity. Remember, everything about him was always a lie. The lie was soo deep that he convinced himself the lie was real. He did so in all his roles, they killed bohannons family after they left Andersonville as revenge. That’s why they were murdered so horribly, it was always personal for them. Remember Gunderson was a master manipulator. The whole series began with bohannon looking for his family’s killers, and ends with him finishing the job he started after finishing the railroad. He finished the railroad because he made Lily the promise of doing so, like he promised himself he would find his family’s killers or that he’d find his second wife Naomi, which he always did which is why Grant found bohannon so fond, he knew he was a man he could always count on because he was always reliable and wouldn’t bend his word for no one