CIVIL WAR COPPER OR BRASS PERCUSSION CAP BOX?

I dug only the lid of this item, which I cannot definitely identify. It's made of copper or brass and sports the cannons and flaming cannon ball motif. These is a cross covering the cannon ball. I speculate that the piece is the top of a percussion cap box, though I've never seen one like it.

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It came from Union lines opposite the Confederate Texas redoubt near the VNMP.