The interesting find is that inside the cover was a notation that this copy once belonged to William Rosecrans, commander of the Union army at Chickamauga. But as I read the book I found four pages that had hand written notations on them. They are in pencil so they are not the clearest copies. All the notations center around the time when Wood's Division moved out of the lines on September 20, right before Longstreet assaulted that very spot and turned the tide toward Confederate victory.
This is page 112 with the simple notation, "mistake"
Page 116 with the notation, "[?] Sheridan [?] way to shore up the left of our lines"
Page 127 with the notation, "this is a weak argument to expect a [?] [?]"
Page 128 with the notation, "this is a great mistake"
Is it Rosecrans' handwriting? I have no idea. I only offer it up as an interesting quirk of research. I did find this letter by Rosecrans to allow for some handwriting comparison. My initial reaction is that it does not eliminate the possibility that the writing in the book is Rosecrans'. I'd like to think it is Rosecrans' writing, it seems like an odd hoax to make.
I also posted this pictures on the Civil War West Yahoo discussion group when I found it a few years back. The pictures there might be a bit clearer, I think I scanned them differently back then.