Some of you may be familiar with the book "Terrors and Horrors of Prison Life, or Six Months a Prisoner at Camp Chase, Ohio" The book was published in 1907 by William Hiram Duff a member of the 25th Louisiana who had been taken prisoner at Utoy Creek near Atlanta in August of 1864.
I was able to find his Find A Grave Memorial under W. H. Duff and he is buried in Monroe, Louisiana. From the photograph it does not look like he has a Confederate tombstone or any marker suggesting his Confederate service. Just a small slab saying W.H. Duff.
Asking for help from the folks of Louisiana to verify what I have stated and if indeed he does not have a Confederate tombstone to please order him one. He was a great soldier and patriot.