Isabel was born on April 22, 1451, at Madrigal de las Altas Torres, to King Juan II and Queen Isabel of Castile. King Juan had ascended the throne when he was only 14 in 1419. His mother and his uncle, King Ferdinand I of Aragon, had both acted as regents during his teenage years. His first wife, Maria of Aragon, produced a male heir, Enrique, born in 1425, before she died in 1445. King Juan took on a second wife, Isabel, a bride sent from Portugal, in 1447, suggested by his trusted confidant, Don Álvaro de Luna.
