Treaty of Tordesillas

Signing and enforcement

The Treaty of Tordesillas was intended to solve the dispute that arose following the return in 1493 of Christopher Columbus and his crew, who had sailed under the Crown of Castile, from their first voyage. On his way back to Spain, he first stopped at Lisbon, where he requested another meeting with King John II to prove to him that there were more islands to the southwest of the Canary Islands.

After learning of the Castilian-sponsored voyage, the Portuguese king sent a threatening letter to the Catholic Monarchs, King Ferdinand and Queen Isabella, stating that by the Treaty of Alcáçovas signed in 1479 and by the 1481 papal bull Aeterni regis that granted all lands south of the Canary Islands to Portugal, all of the lands discovered by Columbus belonged to Portugal. The Portuguese king also stated that he was already making arrangements for a fleet (an armada led by Francisco de Almeida) to depart shortly and take possession of the new lands. The Spanish rulers replied that Spain owned the islands discovered by Columbus and warned King John II not to permit anyone from Portugal to go there. Finally, the rulers invited Portugal to send ambassadors to begin diplomatic negotiations aimed at settling the rights of each nation in the Atlantic.

On 4 May 1493, Pope Alexander VI (Rodrigo Borgia), an Aragonese from Valencia by birth, 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, although territory under Christian 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 still belonging 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. By 1493, Portuguese explorers had 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. As the Pope had not made changes, the Portuguese king opened direct negotiations with the Catholic Monarchs 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 Ferdinand and Isabella but had the boundary line moved 270 leagues west ('leagues' being undefined), in order to protect the Portuguese route down the coast of Africa and giving the Portuguese rights to lands that now constitute the eastern quarter of Brazil. As one scholar assessed the results, "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".

Tordesillas meridian

The Treaty of Tordesillas only specified the line of demarcation in leagues from the Cape Verde Islands. It did not specify the length of the league, its equivalent in equatorial degrees, or which of the Cape Verde islands was intended. Instead, the treaty provided that these matters were to be settled by a joint voyage. This voyage never occurred, and instead there were only a series of nonbinding expert opinions produced over the next several decades. Their computations were further complicated by remaining uncertainty about the exact equatorial circumference of the earth. As such, each proposed line can be variously computed using geographical leagues defined in terms of a degree using a ratio which applies regardless of the size of the earth or using a specifically measured league applied to the actual equatorial circumference of the earth, with allowances necessary for the imperfect Portuguese and Spanish knowledge of its true dimensions.

The earliest Aragonese opinion was provided by Jaime Ferrer in 1495 at the request of Ferdinand and Isabella. He stated to them that the demarcation line was 18° west of the most central island of the Cape Verde Islands, equivalent to 24°25′ west of Greenwich. (Harrisse concludes Ferrer must have meant Fogo as this central island.) Thus, Ferrer placed the line at 42°25′ W. on his sphere, which was 21.1% larger than the actual size of the earth. Harrisse further concludes from Ferrer's claim that his league contained 32 Olympic stades (6.15264 km or 3.82307 mi) that his line—if perfectly measured—would have corresponded to a position 2,276.5 km (1,414.6 mi) west of Fogo at 47°37′ W.

The earliest surviving Portuguese opinion is on the Cantino planisphere of 1501 or 1502, generally considered to represent the Portuguese standard map of its day. Because its demarcation line was midway between Cape Saint Roque, the northeast cape of South America, and the mouth of the Amazon River, labeled the Great River (Rio Grande) with an estuary marked "All of this sea is fresh water" (Todo este mar he de agua doçe), Harrisse computed that this line was at 42°30′ W. on the actual globe. 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 Fernández de Enciso. Harrisse computes that Enciso's sphere was 7.7% smaller than the actual size of the earth so his line at 47°24′ W. corresponds to the actual 45°38′ W. based on his other numerical data. Enciso further described the coastal features near which the line passed, but in a very confused manner that might place the line as far west as the mouth of the Amazon between 49°W and 50°W.

Antimeridian: Moluccas and Treaty of Zaragoza

Initially, the line of demarcation did not encircle the earth. Instead, Spain and Portugal could conquer any new lands they were the first to discover, Spain to the west and Portugal to the east, even if they passed each other on the other side of the globe. But Portugal's discovery of the highly valued Moluccas in 1512 caused Spain to argue in 1518 that the Treaty of Tordesillas divided the earth into two equal hemispheres. After the surviving ships of Magellan's fleet visited the Moluccas in 1521, Spain claimed that those islands were within its western hemisphere. The Treaty of Vitoria, negotiated between Spain and Portugal on 19 February 1524, called for the Junta of Badajoz to meet in an attempt to reach an agreement on the antimeridian, which ultimately failed. It was finally agreed in the Treaty of Zaragoza (or Saragossa), signed on 22 April 1529, that Spain would relinquish its claims to the Moluccas upon the payment of 350,000 ducats of gold by Portugal to Spain. To prevent Spain from encroaching upon Portugal's Moluccas, the antimeridian was to be 297+1⁄2 leagues or 17° to the east of the Moluccas, passing through the islands of Las Velas and Santo Thome. This distance is slightly smaller than the 300 leagues determined by Magellan as the westward distance from los Ladrones to the Philippine island of Samar, which is just west of due north of the Moluccas.

The Moluccas are a group of islands west of New Guinea. However, unlike the large modern Indonesian archipelago of the Maluku Islands, to 16th-century Europeans the Moluccas were a small chain of islands, the only place on earth where cloves grew, just west of the large north Malukan island of Halmahera (called Gilolo at the time). Cloves were so prized by Europeans for the medicinal uses that they were worth their weight in gold. 16th- and 17th-century maps and descriptions indicate that the main islands were Ternate, Tidore, Moti, Makian and Bacan, although the last was often ignored even though it was by far the largest island. The principal island was Ternate at the chain's northern end (0°47′N, only 11 kilometres (7 mi) in diameter) on whose southwest coast the Portuguese built a stone fort (Forte de São João Baptista de Ternate) during 1522–23, which could only be repaired, not modified, according to the Treaty of Zaragoza. This north–south chain occupies two degrees of latitude bisected by the equator at about 127°24′E, with Ternate, Tidore, Moti, and Makian north of the equator and Bacan south of it.

Although the treaty's Santo Thome island has not been identified, its "Islas de las Velas" (Islands of the Sails) appear in a 1585 Spanish history of China, on the 1594 world map of Petrus Plancius, on an anonymous map of the Moluccas in the 1598 London edition of Linschoten, and on the 1607 world map of Petro Kærio, identified as a north–south chain of islands in the northwest Pacific, which were also called the "Islas de los Ladrones" (Islands of the Thieves) during that period. Their name was changed by Spain in 1667 to "Islas de las Marianas" (Mariana Islands), which include Guam at their southern end. Guam's longitude of 144°45′E is east of the Moluccas' longitude of 127°24′E by 17°21′, which is remarkably close by 16th-century standards to the treaty's 17° east. This longitude passes through the eastern end of the main north Japanese island of Hokkaido and through the eastern end of New Guinea, which is where Frédéric Durand placed the demarcation line. Moriarty and Keistman placed the demarcation line at 147°E by measuring 16.4° east from the western end of New Guinea (or 17° east of 130°E). Despite the treaty's clear statement that the demarcation line passes 17° east of the Moluccas, some sources place the line just east of the Moluccas.

Effect on other European powers

The attitude towards the treaty that other governments had was expressed by France's Francis I, who declared, "The sun shines for me as it does for others. I would very much like to see the clause of Adam's will by which I should be denied my share of the world."

Treaty of Madrid

On January 13, 1750, King John V of Portugal and Ferdinand VI of Spain signed the Treaty of Madrid, in which both parties sought to establish the borders between Brazil and Spanish America, admitting that the Treaty of Tordesillas, as it had been envisioned in 1494, had been superseded, and was considered void. Spanish sovereignty was acknowledged over the Philippines, while Portugal would get the territory of the Amazon River basin. Portugal would relinquish the colony of Sacramento, on the left bank of the River Plata in modern-day Uruguay, while getting the territory of the Seven Missions.

Following the Guarani War, the treaty was annulled by Spain and Portugal in the Treaty of El Pardo (1761). The border was eventually settled in the First Treaty of San Ildefonso in 1777, with Spain acquiring territories east of the Uruguay River and Portugal acquiring territories in the Amazon Basin.