I think post Civil War but I have not even been able to date the early pans closer than to about 10-20 years. For all I know your pans could be somewhat after 1900 or may have been made for decades. I have two users recently that I have had for a long time but I turned them in to frequent users.
Vose & Co. was in business under that name from 1848-61 so I know the age, more of less, of those two pans. I was able to find a stove catalog that had been reprinted but with no cookware shown. Just enough more about the company that I was able to find out more about my pans and the dates in another book source I have. Those two skillets are more primitive than most early skillets and look their age but are in very good condition. The first pan I got from ebay was marked OSE & Co. but that didn't seem right and it looked like the first letter had gotten shaved off, fallen off, etc. the pattern. So I started with A to Z to see which letters would work in front of OSE. Vose was one of them and I may have looked it up. Those two pans are two of a very low number of early skillets that I know either the maker or the date, generally not both. A lot of guessing is what I do. The Vose skillets are a 7 and a 9 and match each other. I really like using them and, from use, they are now pretty well seasoned.