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 only a few inconclusive skirmishes resulting. For his part, Cervera was content to wait, hoping for bad weather to scatter the Americans so that he could make a run to a position more favorable for engaging the enemy. However, U.S. land forces began to drive on Santiago de Cuba, and by the end of June 1898, Cervera found himself unable to remain safely in the harbor, and Governor-General Blanco y Erenas wanted a sortie, stating, "it is better for the honor of our arms that the squadron perish in battle ...". The breakout was planned for 09:00 on Sunday, July