After being rejected by Portugal’s King John II, who correctly doubted his calculations, Christopher Columbus spent years trying to secure funding for what he believed would be a faster route to Asia. The Italian explorer had already been turned down by Genoa and Venice by the time he approached Spain’s Ferdinand of Aragon and Isabella of Castile in 1486. Though his calculations were indeed flawed, Columbus’ fortunes changed in 1492 after the Spanish monarchs conquered Granada, the last Muslim stronghold on the Iberian Peninsula.
With funding secured, Columbus set sail on August 3, 1492, not toward Asia but into the unknown waters of the Atlantic Ocean, unaware that his voyage would change the course of history.