Should the nonexistent Spanish Armada have sailed into St. Mary's River in 1898, however, bent on doing harm to the volatile border betwixt Florida and Georgia, they would have been faced by Fort Clinch's mix of Civil War-era armament, such as these 10-inch Columbiads. Fort Clinch today has ten of these guns lining the walls, in addition to the one at the park's entrance.

A note on gun nomenclature: I often refer to such guns as Rodman Guns. Rodman Guns were Columbiads, cast in an advanced way that helped them to better withstand the pressure of continued firing, developed by US artilleryman Thomas Jackson Rodman just prior to the Civil War. Are the cannon at Fort Clinch Rodman Guns, or old-school Columbiads? Both styles of gun sure look similar, so you may refer to them with whatever term is more fun for you to pronounce.