Columbus and Spain's Westward Voyages

Christopher Columbus, of Genoese origin, born around 1451, developed a project to reach Asia by sailing west across the Atlantic. His plan rested on a mistaken calculation of the Earth's circumference that badly underestimated the distance between Europe and Asia, influenced by the cosmographer Paolo dal Pozzo Toscanelli and by Pierre d'Ailly's "Imago Mundi." He first presented the project to King John II of Portugal around 1484-1485, who rejected it after his nautical experts correctly judged the estimated distance far too short, and Columbus then sought support unsuccessfully at several European courts before finally winning the backing of the Catholic Monarchs, Isabella I of Castile and Ferdinand II of Aragon, after the conquest of Granada in January 1492 freed up royal resources and attention.