Isabella I of Castile

Isabella married Ferdinand II of Aragon in Valladolid, uniting the kingdoms of Castile and Aragon. This dynastic union laid the foundation for the unified Spanish monarchy and enabled joint policies including the Reconquista and overseas exploration.

Isabella obtained papal approval to establish the Spanish Inquisition in Castile, aimed at maintaining Catholic orthodoxy among converted Jews and Muslims. The Inquisition operated under royal control, conducting trials and executions for heresy.

Isabella and Ferdinand completed the Reconquista by capturing the Nasrid kingdom of Granada. The surrender of the last Muslim state in Iberia ended 781 years of Islamic rule and unified Spain under Christian rule.

Isabella and Ferdinand issued the Alhambra Decree ordering the expulsion of all Jews from Spain who refused conversion to Catholicism. An estimated 40,000 to 200,000 Jews were forced to leave, causing demographic and economic disruption.

Isabella agreed to fund Christopher Columbus's expedition across the Atlantic, providing three ships and supplies. Columbus reached the Bahamas on October 12, initiating sustained European contact with the Americas and the Spanish colonial empire.

Isabella and Ferdinand negotiated the Treaty of Tordesillas with Portugal, dividing newly discovered lands outside Europe along a meridian 370 leagues west of the Cape Verde islands. This agreement shaped colonial claims in the Americas and Africa.