I am a direct descendant of WJC Smith. I have the same problem finding information on John Smith. I thought that he came to Iowa, via Illinois in 1848 then to Clarke in 1855 with the family. Then John disappeared and I can find no other info on him, even death records. The family info from Connie Tierney could be correct. But there must be a definite tie to the Ervin M. Smith Sr because Eaury, WJC and Maria resided with both Sr and Jr in the census rolls. There seemed to be a few other brothers also: James, John C., Wm R.
If John's father, John P./Sarah, came from Va, I might have further info. I would need to know what part of Va. if it possibly is Bedford County. There are several names that keep following down like, Guy, William, John. Possibly his parents could be Bowker and Judy. But nothing is verified at this time. To whom of the Smiths are you connected?