Who was Rui Faleiro and how did he support Ferdinand Magellan’s plans?

Rui Faleiro was a Portuguese cosmographer who played a pivotal role in Ferdinand Magellan’s expedition to reach the Spice Islands by sailing westward.1

Faleiro supported Magellan’s plans by providing the scientific and navigational expertise necessary to argue that the Spice Islands fell within the Spanish hemisphere according to the Treaty of Tordesillas. Together, they traveled to the court at Valladolid in 1517 to present their proposal to King Charles I, who granted them royal assent in 1518.1

The two men were appointed joint captains general of the expedition and were promised the government of any lands they discovered, along with a share of the profits. Both were also invested with the Order of Santiago. However, Faleiro did not ultimately join the voyage; his mental instability prevented him from sailing, leaving Magellan to lead the expedition alone.1