From the stone in front of the gun: 3-INCH ORDNANCE RIFLE MODEL 1861 Field gun made in 1863 for Union forces by Phoenix Iron Co., Phoenixville, PA. Wrought iron Diameter of bore 3 inches Overall length 73.3 inches Weight 816 pounds Fired 9-pound shell 3972 yards (2.25 miles) Was this weapon used at Fort Monroe? The stone is suspiciously silent on this matter.