Although we've ended this thread, I came upon my note of display of captured US flags at Richmond's Libby Prison, and copy for general info:

"Captured Flags. The walls of the office at the Libby Prison are now adorned with a large number of flags captured from United States troops, among which are five fine silk ones and two guidons. The flags are of the Stars and Stripes pattern, and one of them taken at Vicksburg is spattered with blood." ["The Daily Dispatch," Richmond, VA, 4 April 1863.]