The Treaty of Tordesillas signed at Tordesillas (now in Valladolid province, Spain) on 7 June 1494 and authenticated at Setúbal, Portugal, divided the newly discovered lands outside Europe betweenPortugal and Castile along a meridian 370 leagues west of the Cape Verde islands (off the west coast of Africa). This line of demarcation was about halfway between the Cape Verde Islands (already Portuguese) and the islands entered by Christopher Columbus on his first voyage (claimed for Castile), named in the treaty as Cipanguand Antilia (Cuba and Hispaniola).

The lands to the east would belong to Portugal and the lands to the west to Castile. The treaty was signed by Castile, 2 July 1494 and by Portugal, 5 September 1494. The other side of the world would be divided a few decades later by the Treaty of Zaragoza or Saragossa, signed on 22 April 1529, which specified the antimeridian to the line of demarcation specified in the Treaty of Tordesillas. Originals of both treaties are kept at the Archivo General de Indias in Spain and at the Arquivo Nacional da Torre do Tombo in Portugal.

This treaty worked fairly well as between Spain and Portugal, despite considerable ignorance as to the geography of the New World, but it omitted all of the other European powers. Those countries generally ignored the treaty, particularly those that became Protestant after the Reformation.

Signing and enforcement

The Treaty of Tordesillas was intended to solve the dispute that had been created following the return of Christopher Columbus and his crew, who had sailed for the crown of Castile. On his way back to Spain he first reached Lisbon, in Portugal. There he asked for another meeting with King John II to show him the newly discovered lands.

After learning of the Castilian-sponsored voyage, the Portuguese King sent a threatening letter to the Catholic Monarchs stating that by the previous Alcaçovas Treaty signed in 1479 (confirmed In 1481, with the papal bull Æterni regis that granted all lands south of the Canary Islands to Portugal) all of the lands discovered by Columbus belonged, in fact, to Portugal. Also, the Portuguese King stated that he was already making arrangements for a fleet to depart shortly and take possession of the new lands. After reading the letter the Catholic Monarchs knew they did not have any military power to match with the Portuguese, so they pursued a diplomatic way out. On 4 May 1493 the Aragonese-born Pope Alexander VI (Rodrigo Borgia) decreed in the bull Inter caetera that all lands west and south of a pole-to-pole line 100 leagues west and south of any of the islands of the Azores or the Cape Verde Islands should belong to Castile, although territory under Catholic rule as of Christmas 1492 would remain untouched. The bull did not mention Portugal or its lands, so Portugal could not claim newly discovered lands even if they were east of the line. Another bull, Dudum siquidem, entitled Extension of the Apostolic Grant and Donation of the Indies and dated 25 September 1493, gave all mainlands and islands, “at one time or even yet belonged to India” to Spain, even if east of the line.

The Portuguese King John II was not pleased with that arrangement, feeling that it gave him far too little land—it prevented him from possessing India, his near term goal. As of 1493, Portuguese explorers had already reached the southern tip of Africa, the Cape of Good Hope. The Portuguese were unlikely to go to war over the islands encountered by Columbus, but the explicit mention of India was a major issue. With the failure of the Pope to make changes, the Portuguese king opened direct negotiations with King Ferdinand and Queen Isabella to move the line to the west and allow him to claim newly discovered lands east of the line. In the bargain, John accepted Inter caetera as the starting point of discussion with the Catholic Monarchs, but had the boundary line moved 270 leagues west, protecting the Portuguese route down the coast of Africa, but also gave the Portuguese rights to Brazil. As one scholar assessed the results, with such that “both sides must have known that so vague a boundary could not be accurately fixed, and each thought that the other was deceived, concluding that it was a diplomatic triumph for Portugal, confirming to the Portuguese not only the true route to India, but most of the south Atlantic.”

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 of 24 January 1506. Even though the treaty was negotiated without consulting the Pope, a few sources call the resulting line the Papal Line of Demarcation.

Very little of the newly divided area had actually been seen by Europeans, as it was only divided via the treaty. Castile gained lands including most of the Americas, which in 1494 had little proven wealth. The easternmost part of current Brazil was granted to Portugal when in 1500 Pedro Álvares Cabral landed there while he was en route to India. Some historians contend that the Portuguese already knew of the South American bulge that makes up most of Brazil before this time, so his landing in Brazil was not an accident. One scholar points to Cabral’s landing on the Brazilian coast 12 degrees farther south than the expectedCape São Roque, such that “the likelihood of making such a landfall as a result of freak weather or navigational error was remote; and it is highly probably that Cabral had been instructed to investigate a coast whose existence was not merely suspected, but already known.”

The line was not strictly enforced—the Aragonese-Castilian union did not resist the Portuguese expansion of Brazil across the meridian. 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 was friendly toward Portugal and its discoveries, in 1514 in the bull Praecelsae devotionis.

For a period, the treaty was rendered meaningless between 1580 and 1640 while the Castilian King was also King of Portugal. It was superseded by the 1750 Treaty of Madrid which granted Portugal control of the lands it occupied in South America. However, the latter treaty was immediately repudiated by the catholic monarch. The First Treaty of San Ildefonso settled the problem, with Castile acquiring territories east of theUruguay River and Portugal acquiring territories in the Amazon Basin. Emerging Protestant maritime powers, particularly England and The Netherlands, and other third parties such as France, did not recognize the division of the world between two Catholic nations brokered by the pope.

Tordesillas meridian

The Treaty of Tordesillas only specified the line of demarcation in leagues from the Cape Verde Islands. It did not specify the line in degrees, nor did it identify the specific island or the specific length of its league. Instead, the treaty stated that these matters were to be settled by a joint voyage which never occurred. The number of degrees can be determined via a ratio of marine leagues to degrees applied to the Earth regardless of its assumed size, or via a specific marine league applied to the true size of the Earth, called “our sphere” by historian Henry Harrisse.

• The earliest Aragonese opinion was provided by Jaime Ferrer in 1495 at the request of and to the Aragonese king and Castilian queen. He stated that the demarcation line was 18° west of the most central island of the Cape Verde Islands, which is Fogo according to Harrisse, having a longitude of 24°25’W of Greenwich, hence Ferrer placed the line at 42°25’W on his sphere, which was 21.1% larger than our sphere. Ferrer also stated that his league contained 32 Olympic stades, or 6.15264 km according to Harrisse, thus Ferrer’s line was 2,276.5 km west of Fogo at 47°37’W on our sphere.

• The earliest surviving Portuguese opinion is on the Cantino planisphere of 1502. Because its demarcation line was midway between Cape Saint Roque (northeast cape of South America) and the mouth of theAmazon River (its estuary is marked Todo este mar he de agua doçe (All of this sea is fresh water) and its river is marked Rio grande (great river)), Harrisse concluded that the line was at 42°30’W on our sphere. Harrisse believed the large estuary just west of the line on the Cantino map was that of the Rio Maranhão (this estuary is now the Baía de São Marcos and the river is now the Mearim), whose flow is so weak that its gulf does not contain fresh water.

• In 1518 another Castilian opinion was provided by Martin Fernandez de Enciso. Harrisse concluded that Enciso placed his line at 47°24’W on his sphere (7.7% smaller than ours), but at 45°38’W on our sphere using Enciso’s numerical data. Enciso also described the coastal features near which the line passed in a very confused manner. Harrisse concluded from this description that Enciso’s line could also be near the mouth of the Amazon between 49° and 50°W.

• In 1524 the Castilian pilots (ships’ captains) Thomas Duran, Sebastian Cabot (son of John Cabot), and Juan Vespuccius (nephew of Amerigo Vespucci) gave their opinion to the Badajoz Junta, whose failure to resolve the dispute led to the Treaty of Saragossa. They specified that the line was 22° plus nearly 9 miles west of the center of Santo Antão (the westernmost Cape Verde island), which Harrisse concluded was 47°17’W on their sphere (3.1% smaller than ours) and 46°36’W on our sphere.

• In 1524 the Portuguese presented a globe to the Badajoz Junta on which the line was marked 21°30′ west of Santo Antão (22°6’36” on our sphere).

Effect on other European powers

The treaty was historically important in dividing Latin America, as well as establishing Spain in the western Pacific until 1898. However, it quickly became obsolete in North America, and later in Asia and Africa, where it affected colonization. It was ignored by other European nations, and with the decline of Spanish and Portuguese power, the home countries were unable to hold many of their claims, much less expand them into poorly explored areas. Thus, with sufficient backing, it became possible for any European state to colonize open territories, or those weakly held by Lisbon or Madrid. The attitude towards the treaty that other governments had was expressed in a statement attributed to France’s King Francis I, “Show me Adam’s will!”

Modern claims

The Treaty of Tordesillas has been invoked by Chile in the 20th century to defend the principle of an Antarctic sector extending along a meridian to the South Pole, as well as the assertion that the treaty made Spanish (or Portuguese) all undiscovered land south to the Pole.

The Treaty of Tordesillas was also invoked by Argentina in the 20th century as part of its claim to the Falkland Islands/Malvinas Islands.