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Relations between Portugal and Castile in the
Late Middle Ages – 13th-16th centuries

Vicente Ángel Álvarez Palenzuela
Autonoma University of Madrid


A study of the intense diplomatic relations maintained between the Portuguese and Leonese, afterwards Castilian-Leonese, monarchies throughout the Middle Ages. They were dotted with a series of agreements relating to the internal problems of each kingdom, the mutual relations and the general political situation in the Iberian Peninsula. These relations, except for specific moments of brief warfare, which were sometimes very serious, were friendly and familiar. This didn’t exclude the occurrence of frictions resulting from contrary interests. On both sides of the frontier very similar problems were faced: dynastic confrontations or rebellions of the nobility in which both monarchies usually collaborated closely. Castilian expansion and the resulting imbalance of power in its favour, was the cause of the gravest tensions.


Diplomatic Relations, Castile, International Treaties



Relations between the Portuguese monarchy and the monarchies of Leon or Castile (the Kingdom of Castile was the historical continuation of the Kingdom of Leon) after the unification of the latter two kingdoms show a profundity, intensity and continuity not to be found among any of the other peninsular kingdoms during the Middle Ages, even though these were also very close. The bond between the two went far beyond merely diplomatic relations. The matrimonial unions between the two were so strong and frequent that it is possible to claim that both kingdoms were ruled by a single dynasty during the entire Middle Ages.1

Despite this, any attempt by one or the other to unify both kingdoms was destined to failure, and more often than not, to harsh confrontation leading to prolonged resentment and suspicions which were difficult to overcome.2 The very close relations are, in my opinion, the result of a common historical, cultural, and mental identity, but also of an awareness of the differences between their respective personalities. I make this claim without wishing to give credit to nationalist viewpoints which I consider to be out of place and inadequate for historical analysis.

Birth of Portugal and Guarantees of Growth

The difference between Castilians and Portuguese, however subtle we may think, included a diversity of interests among the ruling aristocracy (Mattoso, 1968, 1968-1969 and 1978). The confrontation which took places between, on the one hand, nobles and ecclesiastics from Braga, and on the other the Trabas and the Gelmírez, and which led to the birth of Portugal, would probably not have taken place if there hadn’t been certain differences. These differences, then, set in train the process by which Portugal evolved from a territory of the Astur-Leonese Kingdom, to a county and finally, a kingdom (Marques da Silva, 1983).

The birth of Portugal as a kingdom didn’t provoke a confrontation with its 'womb,' the Kingdom of Leon. The new political reality fitted perfectly with the Leonese idea of Empire. Impera in ancient Hispania was compatible with the existence of other kingdoms. In practice these kingdoms were of equal dignity and, as well as this, they constituted the most adequate response to the Islamic threat, each one taking charge of the defence of a part of the frontier as well as contributing to the Reconquest (Alvarez Palenzuela, 1999 and 2000). Portugal wasn’t born in confrontation with Léon. Rather, it was born in the ‘womb’ of Léon as a solution to the political-military problems that had arisen.

Because of this, the birth of Portugal didn’t cause any tensions between Léon and Portugal. Recognition of the new kingdom occurred naturally, after simple negotiations. This, however, didn’t prevent the usual tensions between neighboring kingdoms from occurring later on. On the other hand, I consider that the ecclesiastical structure in the new kingdom was the result of confrontation between the metropolitan see of Braga and the metropolitan sees of Compostela and Toledo. The problem of ecclesiastical jurisdiction was the reason for the long delay in pontifical recognition of Portugal as a kingdom. Such recognition had posed no problems for the Leonese monarchy (Amaral, 2000).

Early agreements were aimed exclusively at guaranteeing the existence of Portugal as a kingdom e.g. The Pact of Tuy in June 1137, whose possible effects for Portugal were curtailed by the Almoravid attack on Leiría; the Treaty of Zamora in 1143 (Recuero, 1979 and 2000) where, in completely normal circumstances, Afonso Henriques was made king.

It was also necessary to firmly establish the frontiers of the kingdom, whose very existence called into question, if only theoretically, the divisions of territory agreed between Fernando II of León and Sancho III of Castile in the Treaty of Sahagún on May 23, 1158 (Gonzalez, J, 1960, I, 670; II, 79-82). This was the aim of the talks between Fernando II and Alfonso I in La Cabrera in November of the same year and in Santa María de Palo in December 1159. The Treaty of Lérez in April 1165 was signed by both kings on the basis of complete equality and it arranged the marriage of Princess Urraca of Portugal with the King of León. This was the first of many matrimonial alliances.

Agreements were also reached which attempted to guarantee both existing and future borders, and respective zones for reconquest. The Reconquest was the main concern of both kingdoms when they weren’t disputing each other’s right to existence. Portuguese advances in Alentejo and in the present day Spanish Extremadura posed a threat not only to areas which the Leonese King considered pertaining to his area of expansion, but, when united to the Castilian advance in the south-west, could leave the Kingdom of León without an Islamic frontier.

This grave danger for Léon provides a thorough explanation for the alliance between Fernando II and the Almohads which led to disaster for Alfonso I in Badajoz in 1169. This military action was not aimed against Portugal. It was carried out in defense of vital Leonese interests. Thus, it was perfectly reasonable that two years later when the Almohads attacked Santarém, concerning which the King of León had no plans, the King should send help to his father-in-law and his brother-in-law. This action led to the rupture of Leonese friendship with the Caliphate and harsh reprisals which demolished the Leonese advance to the south of the Tagus River. And it was also a reasonable thing for Fernando II to do battle with his brother-in-law, Prince Sancho, in Argañan in 1180, when the latter invaded the Leonese area of influence. In 1184, Fernando II would save Santarém once again when it was at the end of its tether.

Any kingdom which threatened the unstable equilibrium between the peninsular kingdoms became an enemy of all the others. The rise of Castile in the 1180s and ‘90s gave rise to alliances of the remaining kingdoms against it. The following events had an anti-Castilian aim: the marriage of Alfonso IX of León to Teresa, daughter of Sancho I in 1191 and the Treaty of Huesca (González, 1960, I, p.711) signed by the kings of Portugal, León, Navarre, and Aragon. Given the Islamic threat at the time, this treaty may be considered to have been an act of madness. The result was the defeat of Alarcos, a disaster for Castile, but also, if the policies of the Treaty of Huesca were to be continued, disaster for all. These alliances proved that the essential aim was to prevent a threatening rise of any of the kingdoms.

A coordinated defense against the common enemy was essential but so also was the need to guarantee the equilibrium between the Peninsular kingdoms and, above all, their future growth and expansion. This explains the frequent border treaties which were signed in this period, treaties which alternated with apparently contradictory hostile acts.

The twin objectives, territorial boundaries and a definition of the areas of reconquest were the main items on the agenda at the Truce of Coimbra in November, 1212 (González, 1944, II, p. 383-384, 1960, III, p. 576, and 1984, p.529). The kings of Portugal, Alfonso II, of León, Fernando II, and of Castile, Alfonso VIII, who were present at the talks, as well as reaching agreements between themselves, also decided on a common plan against the Muslims which included a satisfactory distribution of the territories to be conquered (Álvarez Palenzuela, 1998, p.1045). The recent victory at the Navas of Tolosa and the collapse of the Almohads led everyone to hope for a rapid conquest of Islamic territories. It was reasonable to plan for this new situation and forget the insignificant problems of the past.

The Formation and Definition of the Kingdom

For years, internal events in the Christian kingdoms postponed the advance. In the case of Portugal, this period saw the beginning of the tensions between the monarchy and the ecclesiastical hierarchy. This conflict brought into discussion the very definition of the kingdom and at one point there was a threat that Alfonso IX of León would become involved. The talks between Alfonso IX and Alfonso II in Boronal in June, 1219, and those between Sancho II and Fernando III in Sabugal in 1224 (Veloso, 1980) gave rise to the necessary guarantees.

From 1225 onwards the Christian kingdoms, as if they had all been awaiting the same signal, renewed their advance into Islamic territory. León reaped the highest rewards – Cáceres, Montánchez, Mérida and Badajoz but Castile and Portugal also benefited, Portugal conquering Elvas. Then something happened which greatly upset the delicate equilibrium reached at Coimbra: León and Castile became united under the same king, Fernando III. It was an event in which Portuguese intervention - led by Princess Teresa, first wife of Alfonso IX, and also by his second wife, Berenguela – was decisive. Inevitably, there were also hidden factors involved, and it was in order to clear up these that Fernando III and Sancho II met in April, 1231. Existing agreements were ratified thus giving the go-ahead for the continued advance into Islamic territory.

The Portuguese advance was delayed by internal problems which led to the removal of Sancho II and his replacement by his brother Alfonso. A long-standing Portuguese problem: the excessive temporal power of its episcopal hierarchy was the pretext for the development of a sensitive political strategy with international ramifications, which led to the substitution of a Ghibelline prince by a Guelph prince.

The best way to allow everyone to forget this controversial substitution and show the adequacy of the solution was by renewing and completing the Reconquest. On the Portuguese side this led to the successful conquest of the Algarve without great military effort (Crónica, 1856; Mattoso, II, 133-134). However, there was a diplomatic obstacle involved as Castile claimed rights over the Algarve (Mattoso, 1986; Marques, 1994). Perhaps this claim originated in the demand for protection by the Taifa of Niebla from Castile due its condition of vassalage. More probably, it resulted from the putting into effect by Alfonso X of the territorial divisions agreed by Fernando II and Sancho II in the Treaty of Sahagún in 1158 (González Jiménez, 2000, 5).

The complex negotiations over the Algarve reached a preliminary solution at Badajoz in November 1252. Two important starting points were agreed on: the decision to fix the Guadiana as the border and the recognition of the sovereignty of Alfonso X over the disputed territory. (González Jiménez, 2000, 6-11). In May 1253 in Chaves an agreement was reached which recognized Castilian rights over the Algarve, though the territory was ceded as a fief to Alfonso III (García Fernández, 2000, 908) or as the dowry of Beatriz, the illegitimate daughter of the new Castilian King, Alfonso X. Beatriz had already been referred to as Queen of Portugal in documents in May of the same year (Ventura, L. 2000, 47). Afterwards the territory would pass to the first-born child of this marriage on reaching seven years of age.

This was a strange agreement, based on the marriage of a king who was already married. Papal condemnation soon followed and the king was excommunicated. On the other hand, the very active Portuguese upper echelons of society didn’t protest at all. The nobility broke off relations with the king when he renewed attempts to strengthen monarchical authority, attempts which had earlier cost his brother the crown. The above marriage caused concern among the Portuguese nobility as it didn’t satisfactorily resolve the problem of the Algarve. Here the Castilian king still held certain rights in the territory.

It is likely that the relinquishment by Alfonso X of his rights in the Algarve was a result of the revolt of the Mudejars in Andalusia and Murcia in the spring of 1264. Portuguese support was forthcoming for the Castilian king and, perhaps relating to this, an agreement was reached on June 5 of that year when a friendly division of the disputed territories was agreed on (González Jiménez; 1991, doc. 285). The fact is that in September of that year Alfonso X relinquished his rights in the Algarve, except for the right to claim an auxiliary force of fifty soldiers armed with lances (González Jiménez, 1991, doc. 290). From this time on, Alfonso III held complete sovereignty.

This agreement was essential to the relations between both kingdoms. In February 1267 the two kings met in Badajoz to sign a new pact (González Jiménez, 1991, doc. 382; Mendonca, 2000). This pact brought an end to all obligations to provide military aid and the Guadiana frontier was mapped out (de Ayala, 1994). The agreement was also vital in that, free from external problems, and despite delays, Alfonso XIII and above all, Dinis were able to hold a long discussion with the ecclesiastical authorities. This confrontation ended favorably for the monarchy after tough negotiations which ended in 1289.

The rise in monarchical power not only confronted the monarchs with the ecclesiastical authorities, but also with the nobility. The rise of the power of the nobility was a problem in all of the kingdoms. As well as this, it occurred at the same time, which led the kings to collaborate. There was a recognized need to limit this growing power as well as to control the growing French influence in the Peninsula. This French influence provided theoretical support for the nobility, i.e. it was a Guelph scheme opposed to the Ghibelline scheme of strengthening of the monarchy, which had been proposed by the young Iberian kings.

Pedro III of Aragon began a great Mediterranean political project in 1282. This project was necessarily in confrontation with the Anjou and therefore, with France. Sancho IV of Castile (Nieto, 1994), king in the midst of a complex war of succession, also had to adopt a hostile attitude to France. France protected the princes of la Cerda who disputed Sancho’s right to the throne. Yet Sancho also need the friendship of France in order to obtain Papal dispensation for his marriage to María de Molina. The plans of Dinis fitted in with this scheme of things. Dinis wished to strengthen the monarchy, which brought him into confrontation with the nobility, including his mother Beatríz, who returned to Castile, and, above all with his brother Alfonso, who cloaked his position in dangerous judicial arguments.

This explains the marriage of Dinis and Isabel, the saintly queen, daughter of Pedro III, as well as the talks which the kings of Portugal and Castile held in Sabugal in July, 1287. The purpose of the talks was to coordinate the action to be taken against their respective rebels: Prince Alfonso and Álvar Núñez de Lara, Arronches being their impregnable base of operations. At these talks the double marriages of their respective children were planned: the Portuguese heir, Alfonso, with Beatriz; the Castilian heir, Fernando, with Constanza. These plans, after many ups and downs, would be carried out.

Portuguese-Castilian friendship remained firm during the following years, even when Castile and Aragon reached open confrontation between 1289 and 1291 because of the insistence of the King of Aragón, Alfonso III, in improving his borders. In September, 1291 Sancho IV and Dinis again held talks in Ciudad Rodrigo to discuss real problems: a common defense against Islam and the affirmation of monarchical power. Again the proposed marriage of the Castilian heir with Constanza was discussed.

Some months later new talks were held in Ciudad Rodrigo, in April, 1292. Sancho IV asked his Portuguese counterpart for economic help for the offensive he was about to initiate. Despite the affectionate refusal of the Portuguese king, friendship between the kings was not affected.

However, comprehension was not easy as the situation was complex. In the summer of 1293 Sancho IV seemed to reach an understanding with France and the previous marriage plans were cancelled. Again the Guadiana frontier (Serpa, Moura, Mourão) became an object of concern. There were incidents from Ribacoa to the Algarve coast and to the Tagus estuary.

The end of the Reconquest -(only Granada remaining) favored a united kingdom of León and Castile. This fact had fatally broken the delicate political equilibrium forged towards the end of the 12th and the beginning of the 13th centuries. Navarre being isolated and a mere appendix of France for several decades, Portugal and Aragon (whose future expansion could only be overseas) took advantage of any Castilian weakness in order to correct this situation.

This provides an explanation for the following: after the death of Sancho IV of Castile, when his brother Juan, the theoretical leader of the claims of the nobility, disputed the throne, at least that of León, with his nephew Fernando IV (González Mínguez, 1976 and 1995), he could count on Portuguese support after talks with Dinis held in Guarda, probably in July, 1295 (Baquero, 2000, 643).

Momentarily, the problem was resolved by the talks held between the Castilian Prince Enrique and Dinis in Guarda in September of the same year. The Prince offered to hand over Serpa, Moura, and Mourão as well as Aroche and Aracena (García Fernández, 2000, 932). More concessions were agreed on at the talks between Queen María de Molina (Gaibrois, 1935; Hoyos, 1972-739) and Dinis in Ciudad Rodrigo in October at which the effective cession to Portugal of the disputed ‘elbow of the Guadiana’ (recodo del Guadiana) and the above mentioned towns was agreed on.
But, immediately, Jaime II of Aragon (Martínez Ferrando, 1980) started the ancient project of changing the peninsular equilibrium. He now hoped to break up Castile-León’s political edifice, splitting it into two kingdoms with territorial compensations for Aragon and Portugal. This scheme was agreed at Bordalba in January, 1296. The problems of territorial boundaries and the deadlines for handing over territories which Dinis considered to be delaying tactics, justified the militaristic attitude of the Portuguese king and his support for Aragon.

In defense of this project, in September 1296, a Portuguese army led by Dinis himself advanced along the Duero and reached the neighborhood of Valladolid. Nevertheless, when nothing seemed to prevent an entry into the city where the queen lived (regent for her son) the Portuguese king ordered a withdrawal during which the lands around Ribacoa were conquered – this, surely was the true aim of his Castilian adventure- and negotiations were commenced. Apart from the firm support of the Cortes for Queen María, which Dinis soon became aware of, it was a contradiction to promote the strengthening of monarchical authority in Portugal while supporting the power of the nobility in Castile.

The clarification of the boundaries and the return to a more balanced territorial situation were important. However, the political risk was not proportional for those involved. Because of this and because he had something to offer in exchange, Dinis was the first to open negotiations with the prostrate Castilian monarchy, encouraged to do so by the beneficial influence of Queen Isabel. As well as this, Castilian offers were very interesting: a letter from Fernando IV, towards the end of August, 1297, proposed the recognition of the seven fortified towns of the Ribacoa area as belonging to Portugal (Baquero, 2000, 646).

This situation led to the Treaty of Alcañices of the 12 September 1297 (González Jiménez, 2000, 21-24). This treaty, agreed on between Castile and Portugal from an evident position of Portuguese strength, principally contained provisions for a Castilian surrender of territory. Besides the Ribacoa territory (in fact, occupied by Portuguese troops on previous occasions, Ventura, 2000, 38-41), this included the lands which had been given to Castile at the Treaty of Badajoz in 1267. Castile held on to Aroche and Aracena by surrendering territory in the Badajoz area (Lovenza, Campo Mayor, Ouguela), as well as San Felices de los Gallegos. Dinis also symbolically relinquished territories over which he supposedly had authority: Valencia de Alcántara, Ferreira and Esparragal. In exchange for this territorial sacrifice, Castile received something very valuable: the Portuguese king would not intervene in political or military operations threatening for Castile.

Portuguese historians have been right in saying that the Treaty of Alcañices provided a definitive map of the border between the two kingdoms (Amaral-Garcia, 2000). It was also the definitive acceptance of the territorial boundaries which had been drawn up during the previous century and a half.

Collaboration on Common Problems

The Treaty of Alcañices didn’t end Dinis’s intervention in Castilian politics. He was immediately asked by some members of the Cortes, meeting in Valladolid in May 1298, for help against Prince John and his supporters. His behavior, however, showed him to be more inclined to follow the plans for the break-up of the Crown of Castile rather than a sincere attempt to provide aid. This would seem reasonable after the treaty which had been signed and the matrimonial alliances which had been agreed on.

After talks in Toro with Prince Enrique, whose attitude in the crisis was even more dubious, the Portuguese king proposed to Queen María de Molina the surrender of Galicia to Prince Juan, as a way of pacifying the situation. His proposal was rejected and at the request of the Castilian government he returned to his kingdom. However, he remained in places close to the border keeping a sharp eye on what was happening.

In the following months a strengthening of the government of the regent Queen was evident. It was very active and received the vital support of the Cortes. Despite this, many initiatives were frustrated or their success diminished by the strong interests of the nobility who supported her. The nobility had no interest in the destruction of her opponents. The intervention of Dinis inevitably led to a weakening of monarchical positions.

Perhaps it was this reality as well as the consolidation of the Castilian government which moved Dinis to favor the successful outcome of the recent pacts. By his initiative in January, 1300 a new meeting was arranged with the Castilian queen and her son to take place in Ciudad Rodrigo in March of the same year. The official reason cited was the division of the expenditure needed to obtain the bulls of dispensation necessary to be able to proceed with the arranged marriages. We can accept that for Dinis it was better to reach an understanding with the kingdom of his future son-in-law, whose position on his throne appeared to be strengthening, than to support schemes for breaking up Castile: schemes which were losing support everywhere. We should also take into account Queen Isabel’s efforts to bring peace (Lopes, 1967) as well as the growing concern caused by the increasing rebelliousness of Prince Alfonso.

The arrival of the bulls legitimizing the children of Sancho IV and María and the dispensations for the celebrations of the marriages in October 1301 must have removed any doubts from the Portuguese king. Fernando IV and Constanza were betrothed in January 1302. Seven months later Dinis sent a messenger to Castile to fix the date for the consummation of the marriage, as both parties had reached the necessary age (Baquero, 2000, 647).

These events should be seen in the general context of peninsular and Mediterranean peace, despite some military threats. The Peace of Caltabellota was signed in August, 1302 and Jaime II began to set his sights on prospects in Sardinia which were far more attractive than the old dispute over the hereditary rights of La Cerdas. Thanks to the initiative of Aragon, talks were held between Aragon, Castile and Portugal, with the presence of representatives of Alfonse de la Cerda, in Badajoz in April 1303.

The solution proved difficult to come by, and the attempts led to proposals of the most disparate solutions, which always returned to the old scheme for territorial break-up that Jaime II didn’t seem willing to carry out. However, his duplicity caused Dinis increasing unrest and led him to protest against what he considered to be double-dealing. This was what led to the solution by arbitration, when Dinis intervened as the principal actor in peninsular politics.

During the months of March and April, 1304, the final details were fixed in Calatayud and Tarazona for a great meeting to be held, presided over by the King of Portugal, and where the differences between Castile and Aragon would be resolved and the long dispute over the Castilian succession would be brought to an end. Dinis in the month of May in Coimbra accepted the proposed meeting and began preparations for the outward display which characterized his journey across Castilian territory to Torrellas, a place on the Castilian-Aragonese border, between Ágreda and Tarazona.

Dinis acted in Torrellas as the doyen of Iberian sovereigns. It might seem that this was the hour of glory of his reign. However, we shouldn’t allow ourselves to be dazzled by the pomp of the meeting and the festivities. Jaime II was the real victor of this meeting, the one who obtained territorial benefits. The presence of the Portuguese monarch added luster and solemnity to the occasion but it didn’t change anything which had already been agreed on.

The Torrellas Pact only resolved some of the problems presented, in particular, the Castilian succession. It didn’t bring an end to Aragonese maneuvers to force a new peninsular equilibrium which would overrule all preceding territorial pacts, including that of Almizra in 1244 and, certainly, the latest one in Torrellas. Nor did it mean that Castile was in agreement with the border mapped out in Alcañices. At the beginning of 1312, Fernando IV again raised the issue of his territorial claims to the Recodo del Guadiana, Ribacoa, Aroche and Aracena and he appeared to be willing to accept the arbitration of Aragon. The Portuguese side responded with a group of arguments based on the conquest and on the pacts signed by both monarchies in the previous half century.

This situation was largely responsible for a dangerous rise in the power of the nobility. This problem was evident in Castile, above all after 1312, when the early death of Fernando IV, besides bringing an end to the latest Castilian demands, saw the beginning of a new and prolonged regency. Even in Portugal alarming signs became evident: It was more or less during this period that the first confrontations between Dinis and the heir apparent occurred, which would lead soon after to civil war.

A situation of great anarchy reigned in Castile during the following years, the kingdom being divided by the actions of the regency. In general terms, power was disputed by two groups, one representing the power of the nobility, which included the most important Castilian nobles and the relict of Fernando IV, Constanza, and the other, defending royal authority, led again by Queen María de Molina, with the support of her son, Prince Pedro. The successive deaths of the most important personages involved didn’t make the formation of a single government in Castile any easier. Rather, they led to a prolonged confrontation which only began to be resolved from 1325 onwards with the declaration that the new Castilian king, Alfonso XI had attained his majority.

Portugal, with a very different setting, lived through similar problems, the result of a rise in the power of the nobility, which has already been referred to. Tensions started with the dispute among the heirs of Juan Alfonso de Alburquerque, one of whom was Alfonso Sánchez, bastard son of Dinis. The presence of this important personage in circles close to royal power (he had been appointed chief steward and was the visible head of a noble faction) and also that of another bastard son, Pedro, Count of Barcelos, gave real concern to the heir that he was in danger of losing his crown. In any event, the heir considered it evident that the power of these personages nullified the continuing task of strengthening royal power, and severely compromised the future.

In 1319 the Portuguese prince turned to Castile and asked the Castilian queen, María de Molina, who was his mother-in-law for help. He also asked his father to hand him over the administration of justice. The Queen of Castile even asked Dinis to hand over power to his son. A strange situation where the heir, while claiming to act in defense of monarchical power, rebelled against it, supported by a considerable number of nobles; and the king, who with his support for his bastard sons had placed monarchical power in danger, now defended it with the support of his son Alfonso Sánchez, the visible head of the nobility.

Thus began the civil war. The war was the occasion for successive harsh manifestos by Dinis against his son – in June of 1320 and in May and December of 1321- and military actions which led to a real division of the kingdom between Dinis and the heir, Alfonso. Queen Isabel, working patiently and with great difficulty, achieved some periods of respite in the conflict between the two. She was unable to avoid the division of the kingdom under two governments, a situation which occurred before the unexpected death of Dinis in January, 1325.

From that year onwards, a new generation came to power. There was also the beginning of a new way of understanding relations between Castile and Portugal. It was deemed necessary to abandon old territorial disputes and lay the foundation for a more genuine cooperation in resolving problems which were common to both.

Both Alfonso IV in Portugal and Alfonso XI in Castile began their reigns resolved on strengthening the power of the monarchy, using extremely harsh methods if necessary. In the case of Alfonso IV this policy was made manifest in his actions against his stepbrother, Alfonso Sánchez, which included the conviction and execution of Juan Alfonso de Alburquerque, father-in-law and principal support of the latter. In parallel fashion, Alfonso XI showed his firmness when, having failed in his attempts to muster the collaboration of Don Juan el Tuerto, head of the Castilian nobility, lured him to a meeting in Toro (November, 1326) and had him executed.

It was at this time in Toro that talks were held with Portuguese ambassadors where, for the first time, a climate of mutual collaboration for the subjection of their respective nobilities and the renewal of the war against Islam in Granada was achieved. Negotiations were also begun for the marriage of Alfonso XI and María, daughter of the Portuguese king.

During the following months there was an intense exchange of messengers. On the Portuguese side the proposal was brought to completion by arrangements for a double matrimony: besides that of Alfonso XI and María, there was that of the Portuguese heir, Pedro and Blanca, daughter of the Castilian Prince Pedro. It was a kind of replay of the Alcañices system (Diaz Martín, 2000, 1240). Despite the fact that Alfonso and María were very closely related, being double first cousins, the proposed marriage was accepted in Coimbra in December, 1327 and solemnized a few months later in Alfayates.

The marriage of the Castilian king was a very serious step, which can only be understood in connection with the other matrimonial alliance, which meant the surrender of an important and strategic part of the bride’s territorial inheritance to the Castilian monarchy. In fact, the matrimonial alliance meant the breaking of the previous agreement of Alfonso XI with Constanza, daughter of Don Juan Manuel. This led to the rebellion of that powerful noble, the protests of the King of Aragon, Jaime II, grandfather of the bride, and new agitation among the nobility in Castile, linked to similar tensions in Portugal.

For the present, taking advantage of the change of king in Aragon - Alfonso IV succeeded Jaime II, who died in November, 1327- Alfonso XI suggested to the new king of Aragon that they collaborate in the Reconquest, and offered him Almería if he re-conquered it. In October, 1328 a pact of friendship was signed by Aragon, Portugal and Castile which reproduced the situation of 1304 (Baquero, 2000, 651-652). A few months later, in January 1329, agreement was reached on the marriage of the King of Aragon, a widow, to Leonor, a sister of the King of Castile. The above agreements were ratified in the exalted atmosphere of a crusade when, in February 1329, Alfonso XI accompanied his sister to Saragossa for her wedding.

However, stability in the relations between Castile and Portugal didn’t last long. In 1329 the King of Castile met Leonor de Guzmán, who was to become his lover and be treated like a queen, in flagrant disregard for Queen María. Thus may be understood why the successive intrigues contrived by Don Juan Manuel were to eventually find support in Portugal, at least from 1335 onwards, even involving a matrimonial alliance. The proposed marriage involved the daughter of the Castilian noble to Pedro, the Portuguese heir, and the breaking off of this Prince’s previous matrimonial alliance, to be justified by the illness of the bride.

The support of Aragon was also sought against Castile. Aragonese support, weak during the reign of Alfonso IV, became strong from January 1336 with the accession of his son Pedro IV. The fierce personal resentment of the new king towards Castile, and towards his Castilian stepmother, induced him to join the coalition. Doubtless, this new attitude led Alfonso IV of Portugal to lay siege to Badajoz, a strategic maneuver aimed at taking the pressure off rebellious elements in the interior of Castile.

Alfonso XI didn’t divert troops to the Portuguese border: the intervention of troops from the bishopric of Jaén and the Council of Seville was enough to defeat the Portuguese at Villanueva de Barcarrota and force Alfonso IV to raise his siege of Jaén. The Castilian reply, after the rebels were defeated, was very harsh: on the three fronts at Galicia, Ciudad Rodrigo and Badajoz, Castilian troops inflicted serious damage to Portuguese territory. The Castilian fleet defeated a Portuguese fleet and brought destruction near Oporto.

This situation lasted almost three years until November 1338. Neither the efforts of the Portuguese queen, Beatriz, basing her appeal on closeness of kinship, nor those of a papal legate who tried to get the collaboration of both kingdoms in the war against Islam, nor those of France which sought Castilian help against England, could bring hostilities to a halt before this date.

Tensions would only ease when an offensive in Africa became imminent. Control of the Straits was endangered, the Straits being a route of vital importance for Portugal, Aragon, and Castile, and also for their Genoese friends, especially now as war with France seriously endangered the overland routes. Despite this, Portuguese aid was only forthcoming after Castile accepted a stringent set of conditions – among them the separation of Alfonso and Leonor- in July 1340, when the Benimerins had already landed and the Castilian fleet had suffered a serious defeat.

Alfonso IV intervened in the war against Islam, which was surrounded with the solemn atmosphere of a crusade, only after his own daughter and son-in-law came to Portugal and begged him to. The result was the resounding victory of El Salado (30th October, 1340), a definitive defeat of the Benimerins and the starting point for the, as yet poorly defined, Castilian and Portuguese projects in Africa. Even though the offensive continued to the conquest of Algeciras (1344), the huge cost of the war meant that a respite was necessary.

The successful campaign allowed the peninsular monarchs to strengthen monarchical power, a task which they carried out simultaneously. In Portugal, Alfonso IV repressed rebellions of the nobility and reformed the judicial system and the organization of municipal government. In Aragon, Pedro IV issued the Ordenamiento de la Casa, Cancillería y Capilla Reales (a decree concerning the royal household, the Chancery and the royal chapels) and revoked the Privilegio General de la Unión (General Privilege of the Nobility). In Castile, Alfonso XI issued the Ordenamiento de Alcalá (the Alcalá decree).

The Black Plague, the resulting economic and social problems and finally, the death of Alfonso XI in 1350 created a new situation. Military operations were halted and the atmosphere of crusade weakened. For Queen María, not only had the moment for revenge arrived, which her father had tried to prevent, but more importantly, that of guaranteeing the succession of her son to the throne, seriously threatened by the numerous offspring of Leonor de Guzmán and the significant support she enjoyed in the kingdom. As was to be expected, the new Castilian king, Pedro I had the support from the beginning of his Portuguese grandfather. Contacts between the two courts at this time were, doubtless, far more frequent and friendly than is testified by the scanty documentation that remains.

In the meantime, the domestic affairs of the Portuguese royal family began to have political dimensions, including the relationship to the situation in Castile. The affair of the Portuguese heir, Pedro with Inés de Castro, especially from 1345 on, after the death of his wife Constanza, brought back the old danger of the closeness to power of the bastard offspring of the royalty. Inés’s brothers urged the Portuguese prince to ally himself with Juan Alfonso de Alburquerque; he and Queen María shared power in Castile. Queen María was regent for her son. Juan Alfonso was a kinsman of Inés but he was also a son of Alfonso Sánchez, stepbrother of Alfonso IV. Sánchez had caused many problems for Alfonso IV at the beginning of his reign.

Again we have a recurrence of the confrontation between the monarchy and the nobility. This led to a set of bloody moves by Pedro I in Castile, and in Portugal, almost at the same time, where Alfonso IV ordered the execution of Inés de Castro. This measure was designed above all else to avoid a more than possible substitution of his grandson Fernando as heir by one of the sons of Inés de Castro. For the Portuguese king this would have meant a kind of return of Alfonso Sánchez. War broke out in both kingdoms. In Portugal power was practically handed over to the heir and in Castile the king instituted harsh repression.

The parallelism between the two Pedros – the Portuguese one succeeded his father in May 1357 – is complete. Both strove to govern in their respective kingdoms in a personal manner, and neither was very concerned about the violence of many of their decisions. From March, 1358, date of the Treaty of Évora, they were allies: Portuguese ships formed part of the Castilian fleet which that summer harassed the coast of Aragon, the second act in the war between Aragon and Castile. Friendship was again based on matrimonial alliances: a future marriage was arranged between the Portuguese heir, Fernando and Beatriz, daughter of the King of Castile and María de Padilla. Portuguese support for Castile in its operations against Aragon occurred on further occasions. At least during the summer of 1363, there were Portuguese troops in the army that fought on the territories of Aragon and Valencia.

However, in 1366 the Portuguese king refused to become seriously involved in the Castilian Civil War, which was beginning to take a worrying course for the legitimate monarch. In summer, Pedro I traveled to Portugal to request that his Portuguese namesake intervene seriously in the conflict. He made an attractive offer: the fulfillment of the matrimonial alliance which had been decided at Évora and immediate recognition of the Portuguese heir as successor to the throne of Castile. Apart from calculations as to the difficulties of a successful intervention, the Portuguese refusal was probably due to the fact that the proposal involved a union, at least a personal one, between the kingdoms.

The Portuguese king died in January 1367 and from this time, his successor, while maintaining a strict neutrality regarding the Castilian question, strove for closer ties with Aragon. Nevertheless, the death of Pedro I of Castile in March 1369 and the resistance of his supporters would change this situation.

Dynastic Changes

The death of Pedro I didn’t bring an end to the problems of Enrique II. The partisans of Pedro, basing their argument on the rights of Manuel via his mother, Constanza, argued that Fernando I of Portugal was a possible candidate for the Castilian throne. A coalition between Portugal and Aragon, including the collaboration of Navarre and Granada, was thought to be possible.

Fernando I prepared to make his claim effective. A Portuguese fleet attacked in the mouth of the Guadalquivir at the same time as Portuguese troops took possession of Ciudad Rodrigo. Fernando I arrived in La Coruña, the main centre of Petrismo. All this led Enrique II to retaliate. He recovered territory in Galicia and made a profound advance into Portugal as far as Braga and Guimarães. The following year the Castilian fleet broke the blockade which had been enforced by the Portuguese fleet. This didn’t mark the end of Petrismo, which continued to hold out in many parts of Castile, but it did show where real power lay. Nevertheless, a coalition of peninsular kingdoms, including Granada, rose against the Trastámara, aimed as usual at limiting Castilian hegemony in the peninsula.

The taking of Zamora by the Trastamaristas, in February 1371, moved the Portuguese king to seek a treaty with Enrique II. Negotiations for this treaty had been going on for months under the supervision of papal legates. On the basis of the proposed marriage of the Portuguese king to a daughter of the King of Castile, Leonor, the Treaty of Alcoutim was signed on 31 March 1371. The treaty contained important territorial cessions from Castile to Portugal along almost the entire frontier: Allariz, Monterrey, Ciudad Rodrigo and Valencia de Alcántara, as the dowry of the Castilian princess. The surrender of territory didn’t take place, as the marriage of Fernando to Leonor Téllez brought an end to the plans for the marriage arranged at the treaty as well as an end to the need for the territorial compensation which had been agreed on.

From the summer of 1371 on, the Lancastrian design (which was a new version of Petrismo) began to operate. The scheme sought to give the throne of Castile to John of Lancaster who was at the time married to Constanza, daughter of Pedro I and heiress to his titles. This scheme, in furtherance of which England sought the support of Portugal (Russell, 1955) should, perhaps, be considered as providing an explanation for the marriage of Fernando I, a marriage which has usually been considered to be the result of a mere whim. The fact is that when the King of Portugal formed an alliance with the Duke of Lancaster in July, 1372, it was probably, from a military viewpoint the worst moment possible, as a Castilian fleet had just inflicted a severe defeat on an English fleet near La Rochelle: Castile’s naval hegemony had begun.

The Castilian reply was to advance deep into Portugal. Castile had significant support in Portugal and the expeditionary army reached Lisbon where a Castilian fleet lay anchored. Pontifical mediation led to a new peace treaty between both monarchies in Santarém, 19 March 1373. The treaty provided for the marriage of Beatriz, sister of Fernando I, to Sancho, brother of the Castilian monarch. Other matrimonial alliances followed between the children of both kings (Alfonso and Fadrique, bastard sons of Enrique II to Isabel and Beatriz, daughters of Fernando I, Beatriz being a legitimate daughter). These alliances were aimed to strengthen the ties of friendship between both kingdoms.

Peace between the monarchies lasted for some years. At this time there were talks of arranging a marriage between Beatriz and the heir of the new King of Castile, Juan I (Suárez Fernández, 1977) – a utopian project, in reality a strategic maneuver to divert attention – and of having a common position on the question of the Schism, with recognition of the Pope in Avignon. All this coincides with Castilian efforts to achieve neutrality in the Anglo-French conflict. However, the rupture caused by the Schism of the West in the Church and in Christendom (Alvarez Palenzuela, 1982) had serious consequences for Portuguese-Castilian relations. The delicate equilibrium between the two was complicated by the survival of Petrismo and the Lancastrian design to attain the throne of Castile.

Through the mediation of an important Petrista, Juan Fernández de Andeiro, secret negotiations were carried out leading to an Anglo-Portuguese alliance. This alliance made provisions for the marriage of Beatriz to Edmond of Langley, a nephew of the Duke of Lancaster and the sending of an English expeditionary force to Portugal. All of this was agreed in July 1380 by virtue of the agreement signed in Estremoz.

The discovery of these proposals provoked a strong reaction on the part of Castile, which was the prologue to further confrontation with Portugal. It abandoned its transitory neutrality and renewed its alliance with France (April, 1381). It further recognized Clement VII as the legitimate Pope (May, 1381) and it began a new era in its relations with Navarre via the heir to the throne, the future Carlos III.

At the beginning of summer of 1381, Castile began its attacks on the Portuguese frontier, as well as naval attacks which included another blockade of Lisbon. Fernando I made a grave undertaking to recognize Urban VI as the legitimate Pope. Thus the English expedition to Portugal acquired the character of a crusade in favour of Rome. Nevertheless, for English interests which were centerd mainly in Flanders, Portugal was on this occasion, of secondary importance. The English troops who arrived in Portugal were scarce in number and poorly equipped. They behaved like an occupying army, dealing harshly with the people, thereby increasing their disquiet which stemmed from the behaviour of Queen Leonor and the omnipresent power of Juan Fernández de Andeiro.

It wasn’t very surprising therefore, when instead of fighting each other, the two armies negotiated near Elvas. Under the supervision of the pontifical legate, Pedro de Luna, later Pope Benedict XIII (Suárez Fernández, 2002), an agreement was reached in August 1382. This agreement involved a renewal of the Treaty of Santarém as well as providing for a new marriage for Beatriz, to Prince Fernando, the second of the sons of Juan I of Castile. This formula was both more dignified and realistic than that which had been agreed on in previous negotiations. Naturally, Portugal joined those powers that were obedient to Clement VII.

Unquestionably, the Treaty of Elvas left Leonor Téllez and her Petristan supporters in a compromising position, as the illness of Fernando I worsened and made it necessary for them to take steps to secure their future after the king’s death. Barely a few weeks after the signing of the above agreement, the Queen of Castile died, thus offering new possibilities to the ruling group in Portugal.

Effectively, in November of that year, Leonor Téllez proposed that the matrimonial clause in the Treaty of Elvas be modified in the sense that the future husband of Beatriz should be the King of Castile himself (now a widower). Negotiations lead to the cautious Treaty of Salvaterra de Magos in April 1383. This treaty established guarantees preventing a future fusion of the two kingdoms and also satisfied the wishes of the Portuguese rulers, by providing for military backup to keep them in power during the imminent period of the heir’s minority, in quite hostile surroundings. (Suárez Fernández, 1982, 469-475; Arnaut, 1960, 348-355).

For Juan I this risky maneuver had an important compensation: Portugal joined Castile and France in a Clementist group, which was hostile to England. Soon, Navarre and Aragon would join this group when the current heirs took power. The wedding took place in Badajoz in May 1383.
Less than six months after the agreement, Fernando I died. As had been planned, a government headed by Queen Leonor came to power. It had to face strong internal resistance which soon became open rebellion (Coelho, 1984). In Lisbon and Porto, a popular movement (Serrão, 1985; Tavares, 1978) grew whose aim was to prevent Castilian hegemony. Such a hegemony was a grave threat to the Portuguese crafts and to trade, which would have been completely unable to withstand Castilian competition.

The Portuguese situation convinced the Castilian monarch, who apart from enjoying significant support in Portugal received an express request from Queen Leonor to enter Portugal. He did so, establishing himself in Guarda, and demanding that he be handed over complete control of the government, thereby exceeding the powers that had been yielded to him at the signing of the capitulations. At the beginning of 1384, the atmosphere was that of war. From March on, a Castilian force laid siege to Lisbon, which with great severity was continued throughout the summer months. Casualties on both sides were high.

This was the great military campaign which consolidated the figure of João de Avís. Based on his success and on the brilliant judicial arguments of João das Regras in the Cortes of Coimbra in April, 1385 (Tavares, 1983; Bernardino, 1984; Sousa, 1985; Caetano, 1985), the political fortune of Del Master (who became King Juan I) was built. The great victory at Aljubarrota ratified the political decision taken some months before. In international affairs, the new king brought a renewal of the alliance with England and a return of Portugal to the fold of the Roman Pope.
For the Castilian monarchy, the defeat at Aljubarrota, besides bringing on an important internal crisis, from which, nevertheless, it emerged in a stronger position, meant having to confront another English invasion, with Portuguese support, decided on at the Treaty of Windsor in May, 1386. This was a serious threat to the very existence of the Trastámara dynasty and to the territorial integrity of the kingdom. If it had succeeded it would have involved the handing over to Portugal of a substantial group of territories in Salamanca and Extremadura. Again the English expeditionary force had the characteristics of a crusade in defense of the Roman Pontiff.

Anglo-Portuguese collaboration was reaffirmed and became even closer some months after the arrival of the expeditionary force with the matrimonial alliance of Juan I and Philippa of Lancaster, one of the great events guiding the history of Portugal. Despite its apparent strength, it soon became obvious that the English force had no possibilities of success in the Castilian interior. More time was given to negotiations than to combat. Despite the serious obstacles, at the end of July 1388, the Castilian monarch reached an agreement, costly in economic terms. This agreement provided for the marriage of the heir to the throne of Castile with Catherine, daughter of the English aspirant, bringing an end to Lancastrian ambitions in Castile.

The agreement was signed in a general atmosphere of peace. In January, 1389, Castile and Portugal signed six month treaties. In June of the same year, France, England, Scotland and Castile signed three-year treaties, leading to a long ceasefire – it was hoped that it would be definitive- in the Anglo-French War. In November, in Monção, Castile and Portugal also signed three-year treaties, which could be extended, in order to resolve their remaining differences. Portugal joined the general system of Leulingham; the desire for a definitive peace seemed to predominate everywhere.

The Construction of Peace

Despite this, the road to peace between the two monarchies was a long one and was often broken by periods of military conflict, some of which were of significance. The harsh reality of Aljubarrota, with its sequel of human and material losses and desires for revenge would interfere with the peace process, prolonging it for years. The signed treaties were badly observed because of this, and also because of the internal political tensions in Castile after the death of Juan I. The latter circumstance encouraged the more belligerent positions and made diplomatic contacts, already complicated by the internal situation, more difficult.

With the aim of extending the valid treaties, talks were begun in Sabugal and continued in Lisbon. These talks lead to the signing of an agreement in May 1393 which increased the validity of the treaties to 15 years. Thus they could be considered as a providing an excellent foundation for peace (Suárez Fernández, 1960). The contents of the agreement revealed mutual resentment and mistrust, but also a willingness to improve economic relations. It provided for freedom of trade, and the return of property which had been seized, thus establishing the starting point for a return to normal relations.

Some parts of the agreement, especially those pertaining to the return of prisoners, were poorly observed by the Castilians. This eventually lead to new episodes of war especially from 1396 to 1399, and included such radical events as the taking of Badajoz (May, 1396), the burning of Viseu (June, 1397) and the proclamation of Prince Dinis as King or Portugal (May, 1398). The movement of members of the nobility from one kingdom to another was an essential aspect of these confrontations and made peace even more difficult to attain.

After overcoming grave difficulties, new treaties, to last 10 years, and to begin from the following March, were signed in August 1402 (Suárez Fernández, 1960, doc. 32). The tone of these treaties reveals a greater trust between the kingdoms and the desire for an effective peace. This led to special efforts being made to remove the obstacles to peace, to resolve the differences which might arise in the future and, especially, in fixing a precise schedule for the commencement of the appropriate diplomatic contacts.

Despite this express willingness, the proposed contacts were continually postponed. The death of Enrique III and the subsequent problems in Castile brought even further delays. Doubtless, it was the perspective of his access to the throne of Aragon which induced the Castilian Prince Fernando, regent for his nephew, to seek an agreement with Portugal. This agreement was formally signed in October 1411 (Monumenta Henricina, II, doc. 5). It was, in the full meaning of the expression, a peace treaty, which included France and also Aragon, in the event of the Castilian prince being crowned King of Aragon. Because of this, it strove to definitively cancel the past, with the relinquishment of all political demands or claims for injuries, and tried to establish a wide economic basis for future collaboration.

The treaty had to be ratified by Juan II on reaching the age of 14. Despite the desire for peace, the tensions occurring in Castile from 1418 on, with the irruption of the Princes of Aragon in Castilian politics, again raised difficulties for the ratification of the treaty. In 1420 voices were heard in Castile, which refused to accept an automatic ratification of the treaty, and considered a previous show of strength to be essential to force the Portuguese into accepting more stringent conditions.

In spite of the political changeover in Castile – the fall of Prince Don Enrique- difficult negotiations were needed between October 1421 and September 1423 to reach an agreement, not on the previously signed peace treaty, but only on a new ten-year treaty. The terms of this latter treaty had to be completed at later meetings, as negotiations became very complex due to the intervention of Alfonso V of Aragón in Castilian politics. It wasn’t until 1427 that agreement was reached on the additional terms, a stark revelation of the importance of acts of piracy, which both Castilians and Portuguese used against each other.

The control of power by Don Álvaro de Luna, from the middle of 1429 onwards, and surely also the death of Queen Beatriz (daughter of Fernando I of Portugal, and widow of Juan I of Castile), by removing the last obstacle to peace, at last established the adequate conditions for the signing of a true peace treaty. The said treaty was signed in Medina del Campo in October 1431 (Monumenta, IV, doc. 9), and ratified in Almeirim in the following January (Suárez, 1960, doc. 49). It marked the end of a long period of confrontations, and the establishment of an economic and political basis for future understanding.

For quite a number of years, based on these last agreements, relations between the two kingdoms were essentially friendly. There were some scares in relation to maritime expansion, such as the Canary Island question which became an international affair at the Council of Basel (Álvarez, Palenzuela, 1992).

An apparently innocent request by Portugal to the Council gave rise to Castilian suspicions. Portugal requested that a plenary indulgence be granted, in articulo mortis, to the inhabitants of Ceuta and to those of other territories that might be conquered by Portugal. Such vagueness when referring to future conquests was the reason for the protest presented by the Castilian delegation. This led to further protests by both delegations; everything made more complicated by the difficult situation at the Council, due to its confrontation with the Pope.

The unmentioned question which was of grave concern to both delegations was that of the Canary Islands. Portugal had been showing an interest in them, at least since 1418. In 1423 Castilian diplomats protested against proposed Portuguese journeys to the islands.

Concern increased in July 1436 when a Portuguese delegation asked Pope Eugene IV to grant Portugal the right to conquer the Canary Islands. The successive replies of the Pope, while being favorable to Portuguese demands, were extremely careful neither to threaten Castilian interests nor the peaceful situation existing between the two kingdoms. The issue motivated the drawing up of a well-documented report in August 1437 by Alfonso García de Santa María, an important specialist in relations with Portugal.

The discussion on this issue, carried on in a parallel manner in the Curia and at the Council, didn’t lead to a clearly favourable verdict for either party. However, it did lead to heated debates in both places, especially in the commissions of the Council. No definitive conclusion was reached. Nevertheless, the Council’s message to Duarte was practically a request to relinquish all hopes of a favorable verdict, as it was considered that such demands infringed on previous Castilian claims. In any event, both the Castilian and Portuguese presence at the Council was coming to an end. In reality, both delegations had remained longer than was intended, precisely to insure that no decision damaging to their interests was taken in the event of either delegation prematurely abandoning the Conciliar sessions.

Another issue affecting the peace process, without essentially changing anything which had been agreed on, was the presence of the Princes of Aragon in Castilian politics. Portuguese intervention led to the liberation of Prince Don Pedro in December 1432, but Portugal was very careful not to threaten the recently attained peace treaty. After the death of Duarte, Queen Leonor’s abandonment of Portugal and her participation in the renewed struggle of her brothers against Juan II led to another period of tense relations. Naturally, Prince Dom Pedro, Duke of Coimbra, motivated by common interests and political objectives, formed a strong alliance with Don Álavo Luna and the King of Castile. The death of Queen Leonor, and the defeat of the Princes in Olmedo (1445), brought an end for the present, to the threats to peace.

The Consolidation of Peace

The defeat of the princes led to a greater rapprochement between Portugal and Castile. This was especially true of their respective rulers, the Duke of Coimbra and Don Álvaro, who consolidated their personal authority. The external manifestation of this rapprochement was the marriage of the Castilian monarch to Isabel, daughter of the Portuguese Prince Juan, and therefore a granddaughter of the first king of the Avís dynasty. This marriage would prove, however, to be an important obstacle to the political plans of the High Constable of Castile.

The fall from grace of the Duke of Coimbra, despite the fact that his daughter Isabel was the wife of Alfonso V, and his subsequent defeat and death in Alfarrobeira, in May, 1449 (Baquero Moreno, 1973) were events with great repercussions in Castilian politics. In a certain sense, they were a precedent of what would happen in Castile to Don Álvaro. Nevertheless, neither the death of the Duke of Coimbra, nor the subsequent execution of the Castilian High Constable in June 1453 would bring any change in the foreign policy of the two kingdoms: relations continued to be perfectly friendly.

Negotiations for the second marriage of the Prince of Asturias to Juana, daughter of Duarte and Leonor, were begun by Don Álvaro and continued without any change during his imprisonment. Despite the many difficulties involved they were completed fairly quickly, even though the wedding wasn’t celebrated until May 1455, by which time Enrique had been made king. It provided the link for the collaboration between Enrique IV and Alfonso V against the Aragonese.

For Enrique IV, Portugal seemed to provide firm support and even a place of refuge. On the eve of his dismissal in Avila, while he was negotiating the marriage of his stepsister to Alfonso V, he seemed willing to take refuge in Portugal. From Portugal he received promises of military aid when he considered taking violent action against the rebellion of the nobles and the proclamation of Alfonso’s rights to the throne. Afterwards, Guisando’s plans for a marriage between Isabel, now heiress to the throne of Castile (del Val, 1975) and the Portuguese monarch, were seriously considered again. The Portuguese monarch was staunch in his refusal to countenance such an alliance.

The proximity of Portugal to Castilian affairs became an inconvenience at the outbreak of the Castilian Civil War in March 1475. Alfonso V decided to intervene in Castile in defense of the eventual rights of his niece, Juana, the Excellent Lady, who was by then engaged to be married. This action seemed to bring Portuguese-Castilian relations back to the worst times of 1383-1385, with a repetition of many of the events of those years, but now in the opposite direction: a Portuguese invasion of Castile, despite many voices of protest in Portugal itself, the proclamation of the new Queen of Castile, the search for international alliances, in this case with France. The battle of Toro (March, 1476) demonstrated the non-viability of the Portuguese undertaking as well as reaffirming Isabel on the Castilian throne (Suárez Fernández, 2000). However, it wasn’t until February 1479 that another Portuguese defeat brought a decisive end to the war.

Complex negotiations between Beatriz de Braganca and her niece, Queen Isabel during March 1479 led to the signing of a complex peace agreement, the Treaty of Alcáçovas, on 4 September 1479 (Suárez Fernández, 1989; Torre-Suárez, 1958). It didn’t just mean the end of the war, by resolving the issues which had brought it on: it meant a full restoration of relations between both kingdoms to the point they had reached in the Treaty of Medina del Campo-Almeirim.

For this reason the first of the four pacts of the Treaty of Alcáçovas, which restored peace between the two parties, was conceived as a renewal of the ancient peace treaties of Almeirim. The clauses of these treaties were fully transcribed and a new one was added, aimed at resolving problems which had cropped up in the meantime. These more recent issues mainly concerned Portuguese shipping on the African coast, and the islands of the so-called ‘Atlantic-Mediterranean.’ Portugal’s exclusive rights in these zones were acknowledged, as well as Castile’s ownership of the Canary Islands.

The other pacts of the Treaty of Alcáçovas were devoted to solving the problem of the destiny of Juana: the renunciation of her claims to the title of Queen of Castile and her marriage to the Prince of Asturias, with careful clarification concerning the interim tercerías management of the Moura. Future relations were to be firmly founded on family ties – a marriage was proposed between Isabel and Alfonso, with a large dowry, in reality, an indemnity. And a solution to all the problems resulting from the recent war: pardon for rebels and exiles, the release of prisoners and the return of property, etc.

In the full meaning of the term, Alcáçovas marked the end of a journey where the peace treaty, attained with such difficulty at Almeirim, was strengthened. In the following years, relations between the two kingdoms, despite passing through difficult times, would be based not only on friendship, but, even more so, on familiarity. The good understanding had its origins not only in the treaty clauses, but also in the proximity of kinship, consolidated by successive and frequent marriages.

The Treaty of Tordesillas (Tratado, 1995), a union of two agreements signed in June, 1494, provided a climax to Castilian-Portuguese relations during the Middle Ages. The text of the Treaty showed a clear continuity with the entire process I have analysed here; it ratified in their entirety the provisions agreed at Alcácova, which both sides considered to provide a full guarantee for friendly relations. Nevertheless, this last treaty was different from the previous one which was almost completely technical. The Treaty of Tordesillas sought to reply to the new situation which had arisen after Columbus’ first trip.

In fact, the Alcáçovas agreements had resolved the situation created by navigation along the coast of Africa by a partition which followed latitudinal parallels. Now, the existence of lands to the west meant that a division along the lines of the meridians was needed, whatever the limits established were, and some clear definitions regarding Africa. The rest was simply a ratification of that point in relations which had culminated in Almerim and afterwards, in Alcáçovas.




1 This claim may seem to be exaggerated. However, I think it is fully endorsed by the frequent matrimonial alliances between the two ruling families. Five of the nine kings of the first Portuguese dynasty had Castilian wives: Alfonso II, Sancho II, Alfonso III, Alfonso IV, and Pedro I (and to some degree the same could be said of Fernando I). Leonor, wife of Duarte, was also Castilian, even if she was considered to be “Aragonese”, and so were the three successive wives of Manuel I. A very similar panorama is seen in the marriages of the kings of Leon and Castile. Fernando I, Alfonso IX, Fernando IV, Alfonso XI, Juan I, Juan II and Enrique IV all married Portuguese princesses, a tradition which carried through to the 16th century.

I am referring to, on the Portuguese side, to Fernando I’s claim to the Castilian throne, which didn’t have further consequences and to a similar claim by Alfonso V, which lead to his involvement in the Castilian Civil War. On the Castilian side, we have Juan I, whose claim to the Portuguese throne lead to violent confrontation, a civil war in Portugal, and to the disaster of Aljubarrota.




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