Seavey's Island side of Seavey's Island at the former site of Camp Long, a stockade named for Secretary of the Navy John Long, where 1,612 prisoners of war from the Battle of Santiago de Cuba were confined from July 11 to mid-September 1898 during the Spanish–American War. Camp Heywood, a Marine camp named after Colonel Charles Heywood, was located just north of the naval prison. It was occupied after the 1st Battalion's return from Cuba in late August until September 21, 1898. According to the National Trust for Historic Preservation, the Portsmouth Naval Shipyard has 62 buildings listed on the National Register
Battle of Santiago de Cuba and later research by historians, have suggested that nearly 85% of the Spanish ammunition at Santiago was utterly useless, either defective or simply filled with sawdust as a cost-saving measure for practice firing. The American ammunition had no such issues of lethality. "Vizcaya" continued the fight until overwhelmed, and by the end of the engagement she had been struck as many as 200 times by the fire from "Brooklyn" and "Texas". "Brooklyn" had closed to within when she finally delivered an round which, according to witnesses, may have detonated a torpedo being prepared for launch. A huge explosion ensued, "Vizcaya"