I remember hearing of people who had found unexploded Civil War artillery shells and were using them around the house as decorations, thinking that they couldn’t possibly blow up.
On at least one occasion, they thought wrong.
The last Union casualties from Confederate ordnance happened in 1942. Soldiers stationed at Ft. Macon, NC were quartered in a casement and used some old cannonballs for fireplace andirons that exploded.