Castilla was an Aragon-class unprotected cruiser of the Spanish Navy that fought in the Battle of Manila Bay during the Spanish–American War.

In 1870, her design was changed to that of an unprotected cruiser or wooden corvette, and, after political events delayed her construction,[3] she finally was launched in this form in 1881[4] and completed in 1882.

[5] Her original conception as an armored ship and the change to an unarmored one during construction left her with an overly heavy wooden hull that was obsolescent by the time of her launch.

[9] Transiting the Mediterranean Sea, Suez Canal, and Indian Ocean, the division encountered rough weather during its journey only in the Gulf of Lyons.

[5] When the Spanish–American War broke out in April 1898, Castilla was part of the squadron of Rear Admiral Patricio Montojo y Pasarón in Manila Bay.

Her machinery and boilers had been in such poor shape that she was capable only of low speed already, and the only method of stopping the flooding—plugging the hole with concrete—immobilized her propeller shaft, leaving her to rely on sails or towing for propulsion.

At 1030 hours on 29 April 1898, Montojo's ships departed Subic Bay to return to Manila Bay, where shore batteries could support Montojo's squadron and where the shallow water might reduce the loss of life if the Spanish ships were sunk; Castilla again was towed by Reina Cristina on this return voyage.

The squadron anchored later that day in Cañacao Bay off Sangley Point, in the lee of the Cavite Peninsula, about 8 miles (13 km) southeast of Manila.

Castilla and the other Spanish ships opened fire at 0520 hours, beginning the Battle of Manila Bay, the first major action of the Spanish–American War.

She had not been repainted, and still sported her peacetime white sides and yellow funnels, making her an easy and attractive target for American gunners.