Civil War Period Prisoner Carved Bone Fortification Cannon

Exceptionally rare bone fortification with cannons and cassons, American and possibly Confederate prisoner-of-war, circa 1860.  The cannons and cassons are contained in a black painted square shaped glazed case.  The base of the case has an original blue cloth covering.  The perimeter of the model has a bone fortification.  The fence posts are standing cannon barrels with muzzles up. The corner cannons are taller than the others. Each side of the fence has six (6) cannons.  The cannon posts are connected with a rounded bone railing which has angled spikes protecting the fortification from intruders.  There is a flat bone border going around the outside of the fence post with incised diamond patterns.  There are four cannons with turned bone barrels which are shaped like the "Parrot gun" which was developed just before the Civil War.  Each cannon barrel is 2 3/4 inches in length and has a bone sponge inside the barrel.  The cannons are set into bone carriages with bone wheels and limbers.  The carriages have bone ammunition boxes, spoked bone wheels and hand cranks which were used to turn the screw elevator mechanisms.  The back of the limber has a loop which connects over a hook in the facing limber.  The casson is made entirely of bone and has two (2) ammunition boxes.  The four cannons are facing five (5) bone double cassons. The rear casson has a spare bone wheel.  This item is possibly unique and we have never seen anything similar. (MI-523)