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 Admiral Cervera received different treatment than the sailors taken to Portsmouth. For a time, he was held at Annapolis, Maryland, where he was received with great enthusiasm by the people of that city. The Battle of Santiago de Cuba brought Cervera peace of mind that he had fulfilled an officer's duties and that his fleet had upheld Spanish honor. His bravery in the face of the enemy's superiority garnered respect from Spanish and American sailors and officers alike. The Spanish prisoners of war were released upon the signing of the 1898 Treaty of Paris and the remaining Spanish forces left