 Alfonso's mother was Mercedes, Princess of Asturias, but she died in childbirth in 1904.King Alfonso XIII of Spain was unmarried at the time so as the Princess of the Asturias' eldest son, Alfonso became heir-presumptive to the Spanish crown, though, unlike his mother, he never held the title of Prince of Asturias.He was heir-presumptive until the birth of his cousin, Alfonso in 1907, to Alfonso XIII and Queen Victoria Eugenie.