From the Richmond Examiner, 5/20/1864:

AN IRONCLAD YANKEE. - One of the Yankee colonels, received at the Libby from the southside, had his front and rear protected by a patent breast and back-plate, manufactured out of steel, and reputed to be bullet-proof. The colonel confessed that he considered his rear in more danger than his front, especially when it came to running, and, expecting to have some of that to do, providing himself accordingly.