The four brothers that served in the civil war were Daniel, Aaron, Cornelius and Moses. The Reuben you mention would have been from a different family. I have all their pension files. It's curious that while Aaron served in both the 8th Wisconsin and the 4th Minnesota, there is no record of this in his pension file except that he was a veteran volunteer which meant he had served his time and re-enlisted.
I have most of the census records. If you can suggest where I look for the naturalization records that would be helpful.