Not to sound like a mutual admiration society here, but my fellow blogger and new friend John Banks followed up on my earlier post about the letter from a Dr. Flood to the widow of General Joseph Mansfield.
The original letter was purported to be in the Middlesex County Historical Society Museum, which is not far from where John lives in Connecticut. So he tracked it down to the location (housed in the home of the General) and indeed saw the original letter.
He has written his own post about this, with a number of pictures as well … which may be viewed at: http://john-banks.blogspot.com/2012/01/antietam-visit-to-general-mansfields.html
Dr. Flood letter to Mrs. Mansfield (picture by John Banks)
While you are there, be sure to look at his previous post about the “Oliver Case Bible.” I know I’ll be sure to include this fascinating story in certain tours I do in the future at Antietam.
Enfilading Lines 
Randy, thanks to you and John for tracking this down. Last words are always interesting—I contrast the anguished “Am I to die thus?” with Reno’s (paraphrasing here) “I’m dead, Toodeloo.” Two very different personalities, obviously.
Thanks Tim, and thanks for commenting. I’m soon going to put another letter on here with the same overall background scenario. I also still need to get a copy of your most recent book which looks really interesting.
It’s great that your friend was able to track down and document such a historical artifact.