sabella I (1451-1504), queen of Castile, called la Católica ("the Catholic"), and a sponsor of the voyages of Christopher Columbus. She was the daughter of John II of Castile and León by his second wife, Isabella of Portugal. In 1469 Princess Isabella married Ferdinand of Aragón, known also as Ferdinand V, the Catholic. On the death of her brother, Henry IV, Isabella and Ferdinand jointly succeeded (1474) to the throne of Castile and León. Isabella's succession was contested, however, by Alfonso V of Portugal, who supported the claim of Henry's daughter Juana la Beltraneja. Alfonso attacked Castile and León but was defeated by the Castilian army in 1476. Three years later Ferdinand succeeded to the throne of Aragón.
This union of the two main Spanish kingdoms laid the foundation of Spain's future greatness. They had five children, including Catherine of Aragon, the first wife of Henry VIII of England, and Joanna the Mad, who was the mother of Charles V, king of Spain and Holy Roman Emperor. Isabella and her husband (known together as "the Catholic kings") are remembered for initiating the Inquisition in 1478, for completing the reconquest of Spain from the Moors and for their ruthless expulsion of the Spanish Jews, both in 1492. That same year they sponsored Christopher Columbus's voyage, which led to the creation of the overseas Spanish colonial empire, bringing great wealth and power to Spain. [Microsoft Encarta 98 Encyclopedia]