Isabella the Catholic : queen of Spain book. The queen of Castile whose marriage to Ferdinand of Aragon in 1469 marked the beginning of the modern state of Spain; they instituted the Spanish Inquisition Isabella the Catholic, queen of Spain her life, reign, and times, 1451-1504. This book, "Isabella the Catholic queen of Spain," Jean Baptiste Rosario Gonzalve The Spanish queen Joanna of Castille was even more unlucky on the second daughter of Queen Isabella I of Castile and King Ferdinand II of They married in 1469, the year Isabella became queen of Castile. Their two kingdoms were formally united when Ferdinand became king of Arag