Signed on 4th September, 1479, in the Alentejan town of Alcáçovas, and ratified on 6th March, 1480 in Toledo, the former Visigoth capital, the Treaty of Alcáçovas-Toledo put an end to the Iberian conflict which had developed between 1475 and 1479, due to a dispute over the succession to the Kingdom of Castile.
This treaty stood out from the many treaties signed between Portugal and its Castilian neighbours over the centuries, due to its marked effects on the History of the Discoveries and Portuguese Expansion.
This was actually the first treaty that included provisions that not only defined the relations between the Kingdoms in the Peninsula, but also recognised areas of influence outside Europe that the Iberian kingdoms had been exploring over the previous decades.
The dynastic conflict was triggered by the death of King Henrique IV of Castile, in 1474. The succession to the throne disputed between his sister Isabel, wife of Fernando II of Aragon, and Joana, la Beltraneja, daughter of the deceased king. This began a civil conflict between noble factions that supported each of the pretenders, with Isabel counting on Aragonese support.
In an attempt to conquer the throne of Castile, the Portuguese king, Afonso V, supported Joana la Beltraneja's party, asserted himself as her future spouse and led an invasion of Castile, which culminated, in March, 1476, in the inconclusive battle of Toro. After the battle, in face of the rise of Isabel and her supporters, the Portuguese troops were at a strategic disadvantage and were forced to withdraw, returning to Portugal.
The conflict dragged on for the following years, whilst Afonso V sought French support for his pretensions, to no avail, there were military incursions on both sides, and the Catholic monarchs, Fernando and Isabel consolidated their power in Castile. With the peace treaty signed in 1478 between Louis XI of France and Fernando II of Aragon, which ended the prospect of French intervention for good, the negotiation process to resolve the conflict began.
The conflict was also famous for having been the first European conflict to extend overseas. The situation in the Atlantic in 1475 was characterised by a limited Castilian presence on some of the Canary Islands. Portuguese sovereignty, in turn, included not only some of the islands of Madeira, the Azores and Cape Verde, but Portuguese vessels were sailing and trading in the Gulf of Guinea, and gradually advancing southwards.
Over the decades, Portugal sought international recognition of the discoveries made on voyages of exploration. This need grew stronger in the reign of Afonso V, with increasingly large profits from trading in Guinea, and they strove to eliminate outside competition, namely from Castile, and to create an exclusively Portuguese maritime trade. Diplomatic efforts addressed to the Pope resulted in the issue of several bulls, the most important being the Romanus Pontifex, of 1455. The Holy See thus recognised the exclusive rights of the Portuguese Crown in the navigation, trade and dominion of the recently discovered non-Christian regions.
This monopoly was threatened by occasional Castilian attempts to enter into trade in the Gulf of Guinea and by the contestation of Portuguese exclusivity in the region. The outbreak of the war in 1475 heightened this situation, as Fernando and Isabel gave royal support to the attempts by Castilian ships to subvert the policy of naval hegemony and to challenge Portuguese control over African trade.
Thus, accompanying the development of the conflict in the Iberian Peninsula, a privateering war went on in the Atlantic islands and the sea of Guinea. Contrary to the Iberian situation, the Portuguese managed to keep their advantage, as they had more experience and better knowledge of the ocean. However, the battle of privateers between the two kingdoms came to end with the signing of the Alcáçovas-Toledo Treaty.
The first step towards ending the conflict was taken when a meeting was arranged discreetly in the town of Alcântara, in March, 1479. Dona Beatriz, the duchess of Viseu, representing the Portuguese royal family, went to the Castilian town to meet with Isabel. For a week, aunt and niece discussed the foundations for the agreement. The duchess was thus able to safeguard the Atlantic interests of her family.
Then, in the summer of that year, formal negotiations commenced to put an end to the long-drawn conflict. Representatives of both parties met in the Alentejan village of Alcáçovas, having written two treaties. While the Treaty of the "Terçarias de Moura" resolved the question of succession to the Crown of Castile in favour of Isabel I, the Treaty of Alcáçovas-Toledo aimed to terminate the disputes between the kingdoms of Portugal and Castile.
Regarding the Iberian Peninsula, this treaty re-established the former status quo with the mutual return of lands conquered and prisoners captured. As for maritime expansion, the treaty, where the influence can be seen of the prince and heir, the future King João II, defined zones of influence for the very first time.
Thus the Portuguese Crown abandoned all claims over the Canary Islands, which remained under Castilian influence. Castile, in turn, recognised Portugal's right to control the kingdom of Fez, in Morocco, and to possess the archipelagos of Madeira, the Azores and Cape Verde. Even more important was the recognition of the sovereignty and exclusivity of Portuguese navigation in all discovered and hitherto undiscovered lands.
Consequently the Portuguese monopoly of trade on the Coast of Mina and the Gulf of Guinea was confirmed. Portuguese hegemony was thus safeguarded by the recognition of the Holy See, which confirmed the treaty in 1481 through the Aeterni regis bull, and the bilateral agreement with the principal rival in power, the kingdom of Castile.
The Treaty of Alcáçovas-Toledo not only represents the first division of marine territory in spheres of influence, anticipating the Treaty of Tordesillas of 1494, but also formalises the Portuguese expansionist programme, creating conditions for its development during the reign of King João II.
Bibliography:
COSTA, João Paulo Oliveira e, "D. Afonso V e o Atlântico - a base do projecto expansionista de D. João II", in Mare Liberum, nº 17, Junho de 1999, pp. 39-71. Idem, D. Manuel I, um príncipe do Renascimento, Lisboa, Temas & Debates, 2007. RADULET, Carmen M., "Os descobrimentos portugueses e o Tratado de Alcáçovas", in Portugal e o Mundo, dir. Luís de Albuquerque, vol. II, Lisboa, Alfa, 1989, pp. 13-25.
Translated by: Kathleen Calado
