The lead ship, Reina Regente, although otherwise considered excellent, had proven top-heavy, so changes were made to Alfonso XIII to address this, including a smaller main gun.

However, the changes, intended to improve upon Reina Regente, instead left Alfonso XIII lightly armed, slow, and still unstable in heavy seas.

Still incomplete at the time of the Spanish–American War, she was sent to Cadiz on 7 May 1898 to join the Spanish Navy's 2nd Squadron, under the command of Rear Admiral Manuel de Camara, then forming for a voyage to the Philippines.

Due to her incomplete condition, Camara left her behind at Cadiz when his Squadron departed on 16 June 1898 on its abortive voyage.

Alfonso XIII spent the rest of the war in Spanish waters to defend Spain's coast from a potential attack by the United States Navy.