Isabella I Isabella I was the Queen of Castile; who was born in the town of Madrigal de las Altas Torres on 22 April, 1453; and died 26 November, 1504, in the castle of La Mota, which still stands at Medina del Campo (Valladolid). She was the daughter of John II, King of Castile, by his second wife, Isabella of Portugal. Isabella married an arranged suitor, Ferdinand, in the palace of Juan de Vivero, in 1469. On the death of Henry IV, Isabellawas proclaimed Queen of Castile. Ferdinand succeeded to the throne of Aragon, and thus the definitive unity of the Spanish nation was accomplished in the two