This reminds me of Captain Myles Keogh's horse, Comanche, found wandering around the Little Big Horn River a few days after the June 25, 1875 battle. Comanche was preserved and presently resides at the Natural History Museum at the University of Kansas. See http://www.roadsideamerica.com/pet/comanche.html

Now, this makes me wonder if something like that might be done for that Gettysburg "Witness Tree?" Right now, it makes little difference for two or three trees remain on the battlefield, but what about 200 years from now?