[4] After early service in home waters, the Alfonso XII-class cruisers were assigned to colonial duty in the Caribbean and Philippines.

Thanks to machinery and boiler problems, only one was seaworthy during the Spanish–American War, and two were lost during the conflict, one of the sunken ships being salvaged and put into service in the United States Navy.

[1] She was immobilized at Havana, Cuba, by machinery and boiler trouble by 1897, and was anchored only 200 yards (180 m) from the battleship USS Maine when the latter exploded in February 1898.

She was immobilized by boiler trouble at Santiago de Cuba when the Spanish–American War began, and was trapped there along with the squadron of Vice Admiral Pascual Cervera y Topete.

[8] After the annihilation of Cervera's squadron in the Battle of Santiago de Cuba, Reina Mercedes was scuttled as a blockship in the harbor entrance on the night of 4–5 July 1898.