A major biography of the queen who transformed Spain into a principal global power, and sponsored the voyage that would open the New World. In 1474, when Castile was the largest, strongest, and most populous kingdom in Hispania (present day Spain and Portugal), a twenty-three-year-old woman named Isabella ascended the throne. At a time when successful queens regnant were few and far between, Isabella faced not only the considerable challenge of being a young, female ruler in an overwhelmingly male-dominated world, but also of reforming a major European kingdom riddled with crime, debt, corruption, and religious factionism. Her marriage to Ferdinand of Aragon united two kingdoms, a royal partnership in which Isabella more than held her own. Their pivotal reign was long and transformative, uniting Spain and setting the stage for its golden era of global dominance. Acclaimed historian Giles Tremlett chronicles the life of Isabella of Castile as she led her country out of the murky Middle Ages and harnessed the newest ideas and tools of the early Renaissance to turn her ill-disciplined, quarrelsome nation into a sharper, truly modern state with a powerful, clear-minded, and ambitious monarch at its center. With authority and insight he relates the story of this legendary, if controversial, first initiate in a small club of great European queens that includes Elizabeth I of England, Russia's Catherine the Great, and Britain's Queen Victoria.