Federal Civil War Pensions were administered by the Bureau of Pensions which was a part of the Department of the Interior. I have seen correspondence from that bureau where, near the signature of the official signing the document it states "O. W. and N. Division", which had to have been a division within that bureau. I do not know what the initials stand for. Perhaps someone else can shed some light on that. Could someone with the initials OSS have been an executor of his or his wife's estate (ex'r)? I can't think of another explanation of that.
Rick