CODEX Entry 2230: Treaty of Tordesillas
Christopher Columbus, financed by the Crown of Castile, stopped in Lisbon, Portugal, on his way back to Spain. He met with King John II to show objects and maps from the newly discovered lands. King John II sent a threatening letter to the Catholic Monarchs stating that by the Treaty of Alcáçovas, supported by the papal bull Æterni regis, all lands south of the Canary Islands belonged to Portugal. John II also threatened that he was preparing a fleet to take possession of the new lands, principally what is now the Dominican Republic, that Columbus had ‘discovered’. On 4 May 1493 Pope Alexander VI (Rodrigo Borgia), decreed in the bull Inter Caetera that all lands west of a pole-to-pole line 100 leagues west of any of the islands of the Azores or the Cape Verde Islands should belong to Castile, with territory under Catholic rule as of Christmas 1492 remaining untouched. Another bull, entitled Extension of the Apostolic Grant and Donation of the Indies gave all lands belonging to India, to the Spanish, even if east of the line.
The Portuguese King John II had been pursuing the goal of possessing India, and had already reached the southern tip of Africa. John II requested the boundary line moved 270 leagues west, protecting the Portuguese route down the coast of Africa and giving the Portuguese rights to lands that now constitute the Eastern quarter of Brazil. This was granted to Portugal when, in 1500, Pedro Álvares Cabral landed there while he was en route to India. It appears the Portuguese already knew of the South American bulge, so his landing in Brazil was not an accident.
The treaty effectively countered the bulls of Alexander VI but was subsequently sanctioned by Pope Julius II by means of the bull Ea quae pro bono pacis in 1506. The line was not strictly enforced—the Spanish did not resist the Portuguese expansion of Brazil. However, the Catholic Monarchs attempted to stop the Portuguese advance in Asia, by claiming the meridian line ran around the world, dividing the whole world in half rather than just the Atlantic. Portugal pushed back, seeking another papal pronouncement that limited the line of demarcation to the Atlantic. This was given by Pope Leo X, who hated the Borgias and Spanish influence, and was thus amenable to the Portuguese view, issuing the bull Praecelsae devotionis in 1514.
Emerging Protestant maritime powers, particularly England and The Netherlands, and other third parties such as Roman Catholic France, did not recognize the division of the world between only two Roman Catholic nations brokered by the pope.