Prince Carlos, Queen Maria Christina's first cousin once removed, belonged to the deposed royal family of the Two Sicilies and had arrived in Spain years earlier in order to follow a military career in the Spanish army. The pairing of the princess and Prince Carlos was not accidental. He had been chosen as a prospective husband by both Queen Maria Christina and Infanta Isabella, who was his aunt as well. It was considered paramount to marry Mercedes to a member of the Bourbon family in order to avoid a change of the dynasty in case she succeeded her brother. Prince Carlos offered other advantages as groom to the Princess of Asturias. As he did not belong to a reigning royal family, he could settle permanently in Spain and adopt the necessary Spanish nationality. He had, however, to resign to his rights to the crown of the Two Sicilies as he was third in line after his father and his elder brother.