Isabella's half-brother, King Henry IV of Castile, wanted her to marry the king of Portugal. She chose Ferdinand instead, and he crossed into Castile disguised as a servant to reach her. The couple married with a papal dispensation that turned out to be forged. Isabella became queen of Castile in 1474 and Ferdinand king of Aragon in 1479. Together, as the Catholic Monarchs, they completed the conquest of Granada, expelled Spain's Jews and sponsored Columbus's voyages.
In 1468 Henry IV had recognized Isabella as his heir, but he still hoped to control her marriage. Suitors included Afonso V of Portugal, a widower much older than she. Isabella and her advisers preferred Ferdinand, heir to Aragon, whose kingdom's ties to the Mediterranean could balance Castile's power. Negotiations took place secretly.
In October 1469 Ferdinand and a few companions travelled across Castile disguised as merchants, with Ferdinand posing as a mule driver who waited on the others at inns. He reached Valladolid, and the couple met for the first time on October 14. They married five days later, on October 19, at the residence of Juan de Vivero. Because they were second cousins, they needed a papal dispensation; the one they presented was a forgery, and a genuine one was obtained later.
Henry was furious and named his daughter Joanna as heir, which led to a civil war after his death. Isabella won it. The couple ruled their kingdoms separately but in partnership, under the motto "Tanto monta", roughly "one is as good as the other". Their marriage laid the foundation of a united Spain.
Key people: Isabella I of Castile, Ferdinand II of Aragon, Henry IV of Castile