Isabella of Castile should never have been queen. Born on April 22, 1451, she was the second child of King John II of Castile. The king already had an heir, Henry, a 26-year-old son from his first marriage, making him Isabella’s half brother. The king’s second wife, Isabella of Portugal, would deliver a son, Alfonso, two years later, making Isabella third in line.
Her sex and her birth order should have kept her from the throne, but Isabella was a woman who defied the odds. Tough, determined, and iron-willed, Queen Isabella of Castile deftly maneuvered dynastic feuds and political rivalries. Together with her husband Ferdinand II of Aragon, she politically and religiously united Spain, routed the last Muslim stronghold in western Europe, and launched the age of exploration by backing Christopher Columbus. His voyages would lay the foundation for what would become the Spanish Empire. At the height of her power, one European observed, “This queen of Spain, called Isabella, has had no equal on this earth for 500 years.” (See also: Should women rule the world? Queens of ancient Egypt say yes.)
When Isabella was born, Spain was not united. Instead, it was fractured into several small kingdoms. Her father, John II, ruled Castile. Meaning “land of castles,” Castile had once been a small Christian power in northern Spain in the 10th century. As the centuries passed, it grew larger, gradually expanding south as Spain’s Muslim rulers, the “Moors,” were weakening.
