Fragment of explosive shell found near the Citadel. It is from a Navy 12-pdr. howitzer (pictured). It was found on the hill opposite the fort, where the final assault was made from; before US troops could occupy the hill, Korean forces needed to be cleared off.
12-pdr howitzer, as used in the 1871 action
Shell illustration from "Weapons: An International Encyclopedia From 5000 B.C. to 2000 A.D." by The Diagram Group