By José Carlos Palma*

The external projection of Portugal, like other kingdoms, relied on diplomatic maneuvers supported by a complex and effective espionage network. This practice was seen as beneficial for diplomacy, as it allowed ambassadors to extract maximum advantage from their activities. The efficiency of this network, with its unique methods, demonstrated its great usefulness. By having access to information that characterized the political landscape, the king could organize diplomatic missions in a more appropriate manner.

Introduction and Methodology

Despite the recent interest that medieval espionage has aroused in international historiography, existing approaches largely limit the theme to popular works of dissemination. Moreover, some of these works address the issue anachronistically by importing contemporary concepts into the Middle Ages.

In Portugal, the reality is not very different. In fact, the topic of medieval espionage has not received much attention from academics in the historiographical landscape. There are few works that address this theme, and the existing references are essentially limited to considerations found in chapters of Military History books or scattered scientific articles on the subject.

The absence of studies of this nature for the Middle Ages is understandable, as we encounter a lower wealth of documentary evidence and an activity shrouded in secrecy. In fact, there was great care taken to conceal epistolary information through the use of ciphers in order to prevent them from falling into enemy hands. Figures such as D. Duarte, Alfonso the Magnanimous, Fernando the Catholic, and Carlos III of Navarre were among the personalities of that time who used encrypted texts in their correspondence.

The absence of documentary sources is not only a problem in the Portuguese context but also applies to the majority of kingdoms on both sides of the Pyrenees. Therefore, researchers dedicated to the study of medieval espionage in Portugal (as was the case with Vítor Manuel Pinto) rely heavily on chronicle accounts, which provide valuable descriptions and become one of the main sources of consultation. In addition to chronicles, there are other types of documentary sources that may interest researchers and provide important clues about espionage activities. References can be found in texts on political reflection, correspondence, travel accounts, and instructional letters addressed to ambassadors/diplomats, among other scattered types of documentation.

However, despite having a considerable variety of documentary sources at our disposal, we can only comprehend a minimal part of the phenomenon of medieval espionage. It should be noted that, in most cases, it will be impossible to detect the names of the majority of secret agents, as they are omitted, which is understandable given the secretive nature of their activity.

However, when comparing medieval Portuguese espionage to that of the Early Modern period, we notice a significant difference in terms of documentation, both qualitatively and quantitatively, especially for the 16th and 17th centuries. This reality is not only conveyed by us: in the recent publication Les Relations Diplomatiques au Moyen Âge, the same reference is made, stating that there is a noticeable contrast between the works dedicated to the Middle Ages and those focusing on the Early Modern and Contemporary periods.

Given the aforementioned, it is understandable that studies on diplomacy do not allocate more space to the issue of espionage, despite it being “inseparable from the art of war, diplomacy, police, and commerce”. This makes it a highly complex research topic with diverse perspectives, which we cannot delve into in this article. However, it is important to emphasize our purpose: to focus, contribute, and situate espionage within the context of late medieval warfare and foreign policy in Portugal. This period is characterized by intense political dynamism, giving rise to unique features on both the Iberian Peninsula and beyond.

The external projection of Portugal, like other political entities of its time, relied on its diplomatic maneuvers, also supported by a complex and effective network of espionage. Just as it was said in Castile that “the threads woven in the shadows of power were fundamental to the functioning of government, which is why it is not surprising that legal codes authorize espionage”, the same applied to the Crown of Aragon, France, England, and Italy. The latter geographical scope stands out due to its internal antagonisms, which created the ideal conditions for the practice of espionage, without any political authority monopolizing this activity due to internal dissent. However, it is worth noting that the organization of espionage varied from place to place, depending on regional authorities in some cases and central power in others.

Although espionage in the Middle Ages was strongly condemned both morally and legally (as it was considered a crime of high treason punishable by death), we observe that this activity operated according to very specific objectives for the monarch, being encouraged by the politics of the time and widely practiced and disseminated in numerous regions. It served, much like in the present day, as a useful complement to diplomacy, which explains the wide range of valuable information made available to ambassadors, particularly regarding the internal politics of their destination locations. With this in mind, diplomats were able to better prepare their arguments and anticipate counter-arguments from their counterparts based on prior information.

Espionage and spies in the service of diplomacy

Despite there not being a typical portrayal of the medieval spy, this figure emerges prominently during that period. These individuals could come from various social strata, with some of them holding important positions within the palace. However, regardless of the social status of the spies, authorities made efforts to keep them anonymous in order to better adapt to the circumstances of the missions entrusted to them.

It was essential for medieval spies to adopt and adapt to a social identity that allowed them to move covertly, thus concealing their true attributes. Therefore, it was common for political powers in the Middle Ages to use ambassadors or other diplomatic agents as spies, as well as employing individuals who were native to a kingdom, double agents, merchants, travelers, military officers, and even clergy members.

Indeed, the appearance of a spy, including their attire, was highly relevant as it reflected the social or political status of a specific individual (e.g., clergy members and military officers). Assigning a particular habit or clothing style to a person was a common method in espionage during that time. Therefore, it is not surprising that agents tasked with directly spying on foreign entities often disguised themselves as clergy members, merchants, or diplomats in order to acquire the inherent privileges and immunities associated with those social classes.

Diplomats and Embassies

Medieval embassies served as a valuable mechanism for conducting espionage-related activities. Under the guise of diplomatic missions, espionage activities were often carried out with the sole objective of observing and gathering information without the spies being discovered. Due to this, ambassadors were a source of great concern for the courts they visited. The examples of Byzantium and Venice illustrate this concern well. The authorities of these political entities restricted the contact of diplomats with the local populations as much as possible in order to limit the collection of information that would later be sent back to their home courts. In fact, it was common for kings to request their ambassadors to regularly send detailed reports on various aspects, such as the political situation of the places they were stationed in. The history of Portuguese diplomacy provides several examples that illustrate these types of strategies.

Indeed, on the eve of the Battle of Aljubarrota (1385), an embassy led by squire Gonçalo Anes Peixoto was sent with the supposed purpose of making declarations of protest and challenge to King Juan I of Castile. However, as mentioned by Fernão Lopes, the true intention was to “observe well what kind of people they were [in Juan I’s army].” In response, the King of Castile reciprocated by sending a solemn embassy led by Pêro López de Ayala and Diogo Fernandes (brother of Nuno Álvares Pereira) to the Portuguese camp. Their purpose was to spy and gather information about the situation of the forces under the command of the Master of Avis, with the intention of transmitting that information to the Castilians. Years later (1398), still in the context of the war with Castile, João Correia (a knight of the Order of Santiago) was sent to that kingdom as an ambassador to the Master of the Espatários. However, the true purpose of the mission was to cover up acts of espionage.

The examples mentioned can be supplemented with other important facts that deserve our attention, considering the objectives defined for this text. One of these facts is the military conquest of Ceuta, for which Diplomacy played a significant role as a vehicle for espionage. In 1412, King John I of Portugal sent a matrimonial embassy to Sicily, led by the prior of the Hospital and the captain-major Afonso Furtado, with the purpose of offering the hand of Infante Dom Pedro to the widowed queen. However, the reality was different. The true objective of the mission was for the Portuguese ships to dock at the port of Ceuta, both on the outbound and return journeys, so that the ambassadors could observe the city in great detail. As it was a spying mission, they were asked to memorize the gathered information, which proved to be extremely useful three years later.

In April 1456, João Fernandes da Silveira was sent as an ambassador to the Holy See and other Italian political entities. The purpose of this mission was to prepare Portuguese participation in the Crusade that was being organized against the Turks. An unpublished letter of instructions given by King Afonso V to this diplomat allows us to better understand the true scope of this visit to Italian territory. In reality, the mission went beyond the normal objectives of an embassy, as it included a spying aspect: “You will write to us immediately about all the news from there, by those who accompany you and by others, informing us about both friends and enemies”.

Indeed, when reading this document, we can observe that João Fernandes was asked to verify whether the Pope was preparing a fleet, and if so, what its material and human dimensions would be. The same request was made regarding other states, such as Venice, the Holy Roman Empire, Hungary, and Poland. In the case of the Venetians, besides requesting information about the material and human dimensions of their fleet, King Afonso V also wanted clarification on other matters: whether this fleet would join the Pope’s fleet or act independently, how payments would be made, and the amounts involved. As for the other political entities, the Portuguese monarch sought clarification regarding the actions of their military forces: how and when they were mobilized, what weapons they possessed, where they were converging, and what military strategy they intended to implement. Similar information was also requested regarding the Turkish armed forces: their current disposition on the ground, possible combat strategies being considered, and ongoing financing. Specifically, whether they had any islands inhabited by their own people or tributaries, and if so, which ones, whether they paid salaries, how they treated Christians, and how many Christians were among them.

The type of situation we described repeated itself numerous times, as can be seen through an episode that occurred 57 years later. In fact, on January 12, 1513, Gaspar Pereira sent a letter informing King Manuel I that the ambassador of the Preste João king was, in fact, a Moorish spy who most certainly intended to gather data regarding the Portuguese presence in Goa35. The unease and strong competition that this presence represented for Muslims in that region may well have triggered this mission. This unease is clearly inferred when analyzing the correspondence exchanged between King Manuel I and the Viceroy of India, Afonso de Albuquerque. In these letters, information based on espionage activities is reported regarding Dgedah and Suez, Meçua, Preste João, Dalaca, and the Red Sea, among others.

The Natives

The spies known as “internal” or “native” are a category of individuals who belong to the targeted territory but serve the opponent. These are individuals who are familiar with the lands and customs of the regions to be spied upon, which becomes a primary requirement. These individuals were expected to have a command of the local languages as well as an excellent knowledge of the local topography.

In the context of medieval Portugal, these natives were referred to as “línguas,” a term widely used in Portuguese medieval chronicles, particularly in the chronicles of D. Duarte de Meneses and D. Pedro de Meneses. As native individuals, they naturally possessed a good knowledge of the terrain and dialects of the region they were sent to. With their expertise, they played a crucial role in Portugal’s political, military, and diplomatic chessboard in the 15th century, particularly in North Africa.

In this group, we can also include political exiles who would provide vital information about the adversary’s Court. In addition to these men, it is important to mention captives, due to the valuable information that could be obtained from them. Gomes Eanes de Zurara presents us with one such example: he recounts the case of a Moorish captive imprisoned by D. Pedro de Meneses, from whom valuable information about the town of Tangier was obtained, under the promise of being set free.

The Double Agents

A double agent is a spy whose main objective is to infiltrate a target court and gain the trust of key individuals. This allows them to gather accurate information to later transmit to their own lord. In other circumstances, their actions may also involve plans of slander or disinformation, with the intention of misleading the members of the target court. Often, these individuals were also responsible for uncovering other double agents. Generally, these men operated at the court level, as mentioned before, due to the presence of intrigues and ambitions, making it one of the best places for conducting this type of espionage.

Other actions can prove that the Portuguese court, in addition to attaching immense importance to the performance of double agents, was also a target of such intrigues. The actions of Alfonso de Cartagena are one such example. This man was sent to the Court of Avis by the King of Castile (around 1425) with the purpose of obtaining as much information as possible. In order to execute his obligations most effectively, he developed friendships with the Portuguese royal family, particularly with King João I and the esteemed infantes, with whom he established common bonds over the course of 10 years. In this way, Cartagena was able to gather numerous pieces of information, which he later conveyed to his sovereign in the form of letters, ensuring the utmost secrecy of the messages. This mission, it seems, was successful. In fact, it may have been based on Cartagena’s reports that Portugal ultimately lost the fight for the possession of the Canary Islands. This fact would be confirmed by Pope Eugenius IV through the Bull Romani Pontificis (November 6, 1436).

During the regency crisis, between the late 1430s and early 1440s, the widowed queen D. Leonor and Regent D. Pedro used espionage as a means of mutual control, with D. Pedro’s case being the most interesting. According to the information gathered from the Chronicle of D. Afonso V, this prince reportedly employed two maidens to spy on the widowed queen, one being the daughter of Pedro Gonçalves de Malafaia and Isabel Gomes da Silva, and the other of João Vaz de Almada. This case brings our attention to an important question: in the realm of espionage, what role did women play at the court?

In 1448, Martim Mendes de Berredo engaged in double-dealing, conspiring, and acting against the Infante D. Pedro while being a guest in his house, only to later spread successive slanders about the Infante to D. Afonso V. It cannot be said that he was a spy who harmed the kingdom in favor of another, although he was clearly a double agent serving both the king and the Duke of Braganza. (The Duke of Braganza and his sons had the habit of using spies to negotiate their political and military strategies based on the information they provided.)

Rui Galvão is another case associated with this typology. According to Judite de Freitas, in August 1453, this man was sent by D. Afonso V to Castile with the objective of negotiating the marriage of his sister, D. Joana, to the future Enrique IV. In that same year, he would rise to the highest rank of the Castilian royal administration, serving as secretary to Juan II of Castile. This position ensured his integration into the political life of that kingdom, as well as access to privileged information. About two years after this appointment, i.e., in 1455, he returned to Portugal, where he resumed his previous functions. Based on this, Judite de Freitas argues that Rui Galvão acted as a double agent in the Castilian Court, drawing on his extensive diplomatic experience at the highest level, in addition to having a profile very similar to that of spies: fearless and audacious.

Finally, on February 26, 1456, another episode can certainly be associated with the activity of a double agent. It involves a socially prominent Jew who allegedly had access to strategic and confidential information and later transmitted it to the governor of the Moors of Safim. The content of his letter informed that a Portuguese caravel would be heading to the mentioned location to carry out a spying and reconnaissance mission, with the intention of later conducting a military occupation.

The Merchants

In fact, merchants, through their activities that involved extensive travel, had the opportunity to establish wide networks of contacts. Thus, based on these networks, they were aware of the economic, social, and even military realities of the places they visited. To demonstrate the importance of these individuals, we have the request that King Afonso V made to his ambassador João Fernandes da Silveira in 1456: during his mission in Italy, he should speak with the merchants of that region, among other “reliable persons that you find,” in order to obtain information about the Crown’s investments and financial transactions in Bruges, Flanders, Rome, France, and Venice.

For this reason, many spies would disguise themselves as merchants in order to gather as much information as possible while raising minimal suspicion. It is for these reasons that throughout the 14th and 15th centuries, these individuals were viewed with suspicion by political powers, as was the case with the Empire.

According to documentation published in the Monumenta Henricina, dated from June to November 1341, it is known that the Italian city of Genoa had its spies in Portugal. The letters from Florentine merchants, established in Seville, provide us with information regarding the departure of the Portuguese armada from Lisbon to the Canary Islands, as described by Giovanni Boccaccio. In the same compilation of documents, we also found that on December 5, 1414, a Castilian merchant arrived in Portugal, presumably with the task of gathering information about the armada that would depart for Ceuta.

Similarly, the Genoese in Lisbon acted in the same way, as well as the Aragonese spy, Rui Díaz de Vega, in 1415, or even the English. The English, on many occasions, sought to gather information about the state of harvests and, for that purpose, traveled through planting areas with the help of locals. They would then predict future needs and communicate this data to their kingdom so that they could send shipments that were lower than the Portuguese requirements at the appropriate time. This way, they could sell their goods at high prices, as the demand would exceed the supply. In this particular case, England (or another political entity) could benefit in a diplomatic agreement that focused on economic matters, taking advantage of the weaknesses of the enemy.

For the second half of the fifteenth century, we can mention at least two more occurrences of espionage practices associated with merchants. In 1456, King Afonso V sent a ship to the coast of Safim with the intention of eventually conquering it (as previously mentioned). And between 1486-1487, Pêro da Covilhã, disguised as a horse trader, went to Castile to spy on behalf of King João II61.

Travelers

Regarding notes about travelers, there are some references that, along with those of Cardinal Alpedrinha, can be seen from the perspective of a detailed analysis of the places they visited. For example, in the diary of the 4th Count of Ourém, there is a description of Milan. D. Afonso tells us that it is “very large and very rich and well-supplied with all things, except for fish.” This reference could certainly be considered important in terms of gathering economic data, similar to what the English did in Portuguese territory. However, by reading the account, we not only travel back in time but also gain a descriptive perspective of certain aspects of the city. We learn, for example, that the Duke’s castle was very strong and had a fenced area guarded by more than 40 men who could only leave with prior authorization from their captain. We can also get an idea of the size of other cities, such as Pisa, which is “situated in a valley, and its walls are very large, although it was said that Lisbon’s walls were even larger.”

We can see the importance of such accounts in the eventual or hypothetical preparation of future actions, to which we can also add the letters from Italy that Lopo de Almeida sent to King D. Afonso V in the year 1452. This loyal servant of the monarch accompanied the entourage of Infanta D. Leonor to Italy, where she was to marry the Emperor. During this journey, Lopo de Almeida himself tells us that “From Rome, I wrote to Your Highness everything that happened during the arrival of your sister, until her departure from Rome.” For example, in the first letter, found in Volume I of the Proofs of the Genealogical History of the Portuguese Royal House, we see that at a certain point Lopo de Almeida mentions:

According to the disposition of this land [Siena], in my humble opinion, if a strong Emperor were to come here, he would take it all without any delay, especially considering that the people here are not accustomed to fighting in war, unless there is profit without the willingness to fight.

Indeed, while these episodes may not directly relate to espionage practices, they serve as good examples of the importance of acquiring diverse information, including descriptions of certain locations, for the eventual organization of campaigns. Understanding the characteristics and vulnerabilities of different places could significantly contribute to strategic planning and decision-making in military operations.

One well-known example of the association between espionage and travel is found in the figure of Pero da Covilhã, as previously mentioned. This squire of King João II possessed the ideal qualities to carry out such tasks without arousing suspicion. He was a man of low social status by birth, who had spent significant time in Barbary and various European courts, acquiring knowledge of languages such as Arabic, Spanish, and French. In addition to these advantages, he had a deep understanding of the international politics of his time, in which he had been clandestinely involved. For these reasons, in one of the countless espionage missions he was involved in, the monarch “ordered [Pero da Covilhã] to go to Castile because he knew how to speak Spanish, to find out which nobles were taking refuge there.” This mission was part of King João II’s pursuit of several high-ranking nobles involved in conspiracies. Some of these individuals managed to seek refuge in Castile or other kingdoms, such as the Count of Penamacor, who went into exile in England.

The Heralds

The heralds (a subject we recently discussed), due to the position they held, had their activities governed by codes of honor and loyalty. Consequently, they were not likely to be seen as potential spies. However, the reality was different. In fact, heralds took advantage of diplomatic immunity to carry out authentic espionage missions: they observed and took note of events, key points of the places they visited, and kept memories that they reported to the lords they were loyal to. However, according to medieval codes, spying on another kingdom was a clear abuse of their position, thus violating the oath of honor and loyalty they were bound to, as highlighted by João Gouveia Monteiro, based on the Book of Heralds.

The Clergy

The clergy is another social group that could also fulfill this type of role with some ease and discretion. Belonging to a transnational group, according to Armindo de Sousa, made them essential for certain espionage missions, much like merchants. In the 15th century, one such clergyman capable of playing a more active role in espionage missions is the aforementioned Cardinal Alpedrinha. In 1480, D. Jorge da Costa (Alpedrinha) wrote a letter to Prince D. João (future king, the second of his name), in which, among other aspects, he highlighted the political situation in Italy in the late 15th century. Among numerous issues, he warned of the dangers of a Turkish-Ottoman invasion. Indeed, the possibility of a military confrontation was real, especially due to the fall of Constantinople in 1453. As Luís Adão da Fonseca points out in the biography of D. João II, the employment of these individuals was crucial, as they were another piece in the complex chessboard of what would become the future monarch’s intelligence system.

However, due to many clerics, or individuals disguised as clerics, acting as spies (in order to benefit from the immunities associated with their status), this group, throughout the 15th century, came to be viewed as potentially suspicious by various political entities in the West, notably France and England.

The spy networks

Unlike diplomacy, espionage was not a sporadic practice. It was an activity carried out with a certain degree of professionalism and employed frequently by various medieval political entities.

As it is known, the information collected abroad by emissaries, whether or not they belonged to an embassy, was essential to keep diplomats updated. In this way, it ensured that ambassadors made informed decisions based on the agenda and maneuvers of their counterparts.

In other circumstances, the information collected abroad was also crucial. Thanks to this information, it was possible to draft and formalize highly detailed and precise letters of instruction. The letter of instruction that D. Afonso V handed to Álvaro Lopes de Chaves, his royal secretary, is illustrative of this reality. In this document, it is stated that the mission directed to the masters of the military orders of Santiago and Alcántara (in Castile) was planned based on the information transmitted by Cide de Sousa to the Portuguese Court between 1468-1469.

These networks, by the end of the 14th century, showed great organization and specialization: agents carried out the work of gathering, sorting, and systematizing data. Given this, it is not surprising to find the existence of a network of espionage in the service of the Portuguese monarchy, tested in various situations.

Similar to England and France, who spied on each other during the Hundred Years’ War, both militarily and diplomatically, Portugal and Castile would adopt the same attitude during the various conflicts in which they opposed each other. Examples of this can be seen in the activities of Portuguese espionage during the Fernandine Wars, to which Fernão Lopes makes some references to. Regarding King João I, the aforementioned chronicler and Gomes Eanes de Zurara also indicate some occurrences. Even as Master of Avis, João I already had numerous spies in Castile, thus keeping himself informed of all events at that court. Years later, the same can be observed with regards to the Aragonese court (1413) and North Africa, where he ordered the “infiltration among the Moors.”

By doing so, João I kept himself informed of all enemy movements, as well as any diplomatic decisions that could be made to the detriment of Portugal. The monarch thus followed the principles of military strategy outlined by Vegetius, well known among medieval thinkers, which could also be applied to the diplomatic field. Instead of spying on the enemy’s camps, the focus was on spying on their courts, which yielded positive results.

During the same period, the newly elected King of Aragon also utilized his espionage network against two important targets: Portugal and the County of Urgel. In the case of Portugal, the mission of Rui Díaz de Vega aimed to gather information about the fleet being prepared by the Court of Avis, as there were concerns that it might be sent to provide military aid to Jaime de Urgel (unknown at the time that its destination was Ceuta). As for the Count of Urgel, Fernando I had a network of spies meticulously monitoring his every move, as there were fears that he might instigate a rebellion: “due to the many spies he had everywhere, and being new in these realms, he was very wary.” Thanks to this effective and extensive espionage network, Fernando I was able to eliminate internal and external opposition and consolidate his position on the throne.

Another example, dated July 21, 1428, involves another case of espionage: the Castilian monarch, taking advantage of D. Leonor de Medina’s departure, who set off via São Félix dos Galegos on July 21, 1428, sent an observer to Portugal. The purpose of this mission was undoubtedly to gather a series of reports that could be used to his advantage.

In the late 15th century, during the reign of D. João II, Portugal was not only involved in the persecution of its nobility exiled abroad but also engaged in overseas projects. This period is living proof that the construction of João II’s imperial project would not have been possible without a large-scale espionage system, ensured by specialized agents who were trusted by the royal court. These were men who knew how to maintain secrecy and disguise their nationality if necessary. This reality was also present in the subsequent reign, as evidenced by well-documented examples. Therefore, the Prince Perfect could be considered among the most well-informed sovereigns of the world at that time, similar to what had happened in Ancient Rome with Julius Caesar, who was “the first to systematically resort to intelligence and secret diplomacy,” or, for example, his contemporaries such as Louis XI of France, who had informants throughout the Western world, or Francesco Sforza, the Duke of Milan.

This indicates the existence of a hierarchical structure that was undoubtedly the determining factor in complex and effective machinery. An account from the Chronicle of D. Pedro de Meneses demonstrates this in relation to espionage against the Moors. Based on highly precise information about enemy movements, an effective defense of the fortress of Ceuta could be carried out. In 1438, D. Sancho, the brother of the Captain-major of Ceuta, relied on this espionage system when he was sent to negotiate the release of the Holy Infant from the Moors. However, the secret agents discovered that the Muslims had plans to kidnap him, leading to the mission being aborted.

On the other hand, the accounts extracted from the studies of João Gouveia Monteiro, João Marinho dos Santos, and Vítor Manuel Pinto, combined with the chronicles, are equally revealing. It is known that the municipality of Lisbon, like others in the kingdom, made fixed payments to those who served permanently in the espionage network, providing strategic information in return. Let us take as an example certain payments made by this municipality to spies in 1386, although the specific amounts are unknown and less revealing when compared to those mentioned earlier for the seventeenth century.

One of the figures in this efficient espionage machine is the procurator of the municipality. Their responsibility was to make payments to the “enculcas” (spies). As Fernão Lopes states, each of these men was individually well rewarded. The chronicler indicates that the king gave one of them “a very good horse and other things.” However, such benefits were only granted “if they performed this duty and other such things, if they followed the instructions.” Indeed, Silvestre Esteves, one of these men who held the position, was responsible for paying the spies who accompanied the Lisbon host during the siege of Chaves. He served, as one deduces, as a liaison between the secret agents and the monarch, or between the monarch and a prominent palatine member close to King João I.

Conclusion

Taking into account both the chronicle texts and the scattered documentation we have consulted for this study on the contribution of espionage to the diplomatic activity of 15th-century Portugal, it was possible to draw attention to some situations that, until now, have not received much attention in historiographical production.

The cases analyzed allow us to verify that intelligence services, in their various forms, are of crucial importance for the actions of any political entity. This same reality took place in 15th-century Portugal, a period in which espionage was seen as a fundamental tool for safeguarding the interests of the Crown, as well as those who revolved around it, such as the Duke of Braganza and his sons. In this way, the ability to neutralize any type of threat that was evident or to minimize the damages it represented was ensured to the best of their ability.

As we have seen, the adaptability of the entire espionage structure was crucial for the success of secret missions. It should be noted that spies operated in a habitat full of threats. The discovery of their activities could result in corporal punishment or even death. In the case of individuals who were natives working for others, those who were exposed could be sentenced to the loss of their possessions rather than harsher penalties.

However, the risk of being a spy, if successful, was greatly compensated by the monarchs or by the individuals interested in the gathered information. They rewarded spies with favors for the multiple and beneficial military, political, or economic insights they could obtain and use to their advantage. Throughout this work, we have provided examples of such rewards, which can be crucial in interpreting the broader scope of diplomatic activities carried out by Portugal in the late Middle Ages.

Bibliography

• ALBUQUERQUE, Afonso de (2010) — Cartas para el-rei D. Manuel I. Seleção, prefácio e notas de António Baião. Lisboa: Sá da Costa Editora.
• ALMEIDA, Lopo de Almeida (1935) — Cartas de Itália. Ed. Rodrigues Lapa. Lisboa: Imprensa Nacional/Casa da Moeda.
• ARNAUT, Salvador Dias (1947) — A Batalha de Trancoso. Coimbra: FLUC/Instituto Histórico Dr. António de Vasconcelos.
• AZEVEDO, Pedro [Dir.] (1915-1934) — Documentos das chancelarias reais anteriores a 1531 relativos a Marrocos. Lisboa: Academia das Sciências de Lisboa. Vol. 2.
• BAEZA HERRAZTI, Alberto (1994) — « Rui Díaz de Vega, un espía de Aragón en la Reconquista ». Revista Transfretana. nº 6, pp. 33-52.
• BARROCA, Mário (2003) — «História das campanhas: serviços de vigilância». En Nova História Militar de Portugal. Dir. Manuel Themudo Barata e Nuno Severiano Teixeira. Rio de Mouro: Círculo de Leitores. Vol. 1, pp. 86-87.
• BARROS, Amândio (1990) — « A preparação das armadas no Portugal de finais da Idade Média ». Revista da Faculdade de Letras – História, 2ª série. Porto. Vol. 7, pp. 101-132.
• BEGOUM, F. M. (1994) — «Observations on the Double Agent». Studies Archive Indexes. Vol. 6, nº 1.
• BOUCHARB, Ahmed (1994) — «A importância de Safi no império comercial português». Mare Liberum. Vol. 7, pp. 193-201.
• CARRILLO DE HUETE, Pedro (1946) — Crónica del Halconero de Juan II. Edição e estudo de Juan de Mata Carriazo. Madrid: Espasa Calpe, S.A.
• CORTÉS CORTÉS, Fernando (1989) — Espionagem e contra-espionagem numa guerra peninsular: 1640-1668. Lisboa: Livros Horizonte.
• CORTESÃO, Jaime (1997) — A política de sigilo dos Descobrimentos. Lisboa: Imprensa Nacional/Casa da Moeda.
• CUNHA, Maria Cristina; COSTA, Paula Pinto; MARINHO, Duarte de Babo (no prelo) — « Portuguese late-medieval letters of credence and instruction ». E-Journal of Portuguese History.
• DENÉCÉ, Eric e DEUVE, Jean (2011) — Les services secrets au moyen âge. Rennes: Editions Ouest-France.
• DIAS, Aida Fernanda [Ed.] (2003) — Diário da Jornada do Conde de Ourém ao Concílio de Basileia. Ourém: Câmara Municipal de Ourém.
• DINIS, Dias [Ed.] (1960-1974) — Monumenta Henricina. Coimbra: Comissão Executiva do V Centenário da Morte do Infante D. Henrique. 15 Vols.
• DUARTE, D. (1982) — Livro dos conselhos de el-rei D. Duarte: Livro da Cartuxa. Transc. João José Alves Dias. Introd. A. H. de Oliveira Marques e João José Alves Dias. Lisboa: Editorial Estampa.
• DUARTE, Luís Miguel (1989) — «Aspectos menos conhecidos das relações entre Portugal e a Inglaterra na segunda metade do século XV». En Actas Congresso Internacional Bartolomeu Dias e a sua época. Porto: Universidade do Porto/Comissão Nacional para as Comemorações dos Descobrimentos Portugueses. Vol. 3, pp. 551-561.
• DUARTE, Luís Miguel (2003) — «A marinha de guerra, a pólvora, o norte de África: a preparação da conquista». En Nova História Militar de Portugal. Coord. José Mattoso. Dir. Nuno Severiano Teixeira e Miguel Themudo Barata. Rio de Mouro: Círculo de Leitores. Vol. 1, pp. 290-442.
• DUARTE, Luís Miguel (2015) – Ceuta 1415. Seiscentos anos depois. Lisboa: Livros Horizonte.
• ENCARNAÇÃO, Marcelo Augusto Flores Reis da (2006) — A guerra vista do chão: os conflitos militares em Portugal nos reinados Fernandino e Joanino observados numa perspetivo local. Porto: Faculdade de Letras da Universidade do Porto. Dissertação de mestrado.
• FERNADA NUSSBAUM, María (2012) — «Algunas notas sobre los espías en la literatura medieval española de los siglos XIII y XIV». Memorabilia. Boletín de literatura sapiencial. Valência. Vol. 14, pp. 65-76.
• FERNÁNDEZ GALLARDO, Luis (2002) — Alonso de Cartagena (1385-1456): una biografia polítca en la Castilla del siglo XV, Valladolid.
• FICALHO, Conde de (1988) — Viagens de Pêro da Covilhã. Lisboa: INCM.
• FONSECA, Luís Adão da (2005) — D. João II. Mem Martins, Círculo de Leitores, 2005.
• FREITAS, Judite Gonçalves de; CAÑAS GÁLVEZ, Francisco de Paula (2013) — «O agente que serviu as Coroas de Portugal e de Castela: um agente duplo?» En Program, Abstracts & Notebook 5^th European Congress of Medieval Studies. Secrets and Discovery in the Middle Ages. Porto, 25^th-29^th June 2013. Ed. José Meirinho e Lidia Lanza. Porto: Faculdade de Letras da Universidade do Porto/Fédération Internationale des Institutes D’Études Médiévales, pp. 113-114.
• GONZÁLEZ SÁNCHEZ, Santiago (2015) — « El espionaje en los reinos de la Península Ibérica a comienzos del siglo XV ». En la España Medieval. Madrid. Vol. 38, pp. 135-194.
  DOI : 10.5209/rev_ELEM.2015.v38.49040
• LOPES, Fernão (1983) — Crónica de D. João I: Segundo o Códice nº 352 do Arquivo Nacional da Torre do Tombo. Introdução Humberto Baquero Moreno. II vols. Porto: Livraria Civilização.
• LOPES, Fernão (2004) — Crónica de D. Fernando. Edição crítica e introdução Giuliano Macchi. Lisboa: Imprensa Nacional da Casa da Moeda.
• LOPES, Paulo (2005) — Viajar na Idade Média. A visão Ibérica do Mundo no ‘Livro do Conhecimento’. Lisboa: Círculo de Leitores.
• MARINHO, Duarte de Babo (2013) — A família Correia no contexto da Ordem Militar de Santiago: séculos XIII-XIV. Porto: Faculdade de Letras da Universidade do Porto. Dissertação de mestrado.
• MARINHO, Duarte de Babo (2017) — Os embaixadores portugueses nos reinos ibéricos (1431-1474). Um estudo sociodemográfico. Porto: Faculdade de Letras da Universidade do Porto. 2 Vols. Tese de doutoramento.
• MARINHO, Duarte de Babo (2018) — «Diplomacia visual na Baixa Idade Média portuguesa: os oficiais de armas». Medievalista. nº 24.
• MARQUES, A. H. de Oliveira; SERRÃO, Joel [Dir.] (1987-1998) — Nova História de Portugal. Dir. A. H. de Oliveira Marques e Joel Serrão. Lisboa: Editorial Estampa. Vols. 3-5.
• MARQUES, José (1994) — Relações entre Portugal e Castela nos finais da Idade Média. Braga: Fundação Calouste Gulbenkian.
• MARTINS, Miguel Gomes; Filipe, Estevão Vasques (1997) — «O percurso de um guerreiro em finais de Trezentos». Cadernos do Arquivo Municipal. Lisboa. Vol. 5, pp. 10-47.
• MATTOSO, José [Dir.] (1997) — História de Portugal. Dir. José Mattoso. Lisboa: Editorial Estampa. Vols. 1-3.
• MIRANDA, Flávio (2012) — Portugal ant the Medieval Atlantic. Commercial Diplomacy, Merchants, and Trade, 1143-1488. Porto: Faculdade de Letras da Universidade do Porto. Tese de doutoramento.
• MONTEIRO, João Gouveia (1998) — A Guerra em Portugal nos Finais da Idade Média. Lisboa: Notícias.
• MONTEIRO, João Gouveia (2002) — «As comunicações em tempo de guerra». En As Comunicações na Idade Média. Coord. Maria Helena da Cruz Coelho. Lisboa: Fundação Portuguesa de Telecomunicações, pp. 172-189.
• MONTEIRO, João Gouveia (2003) — «De D. Afonso IV (1325) à Batalha de Alfarrobeira (1449). Os desafios da maturidade: exploração do terreno e espionagem». En Nova História Militar de Portugal. Dir. Manuel Themudo Barata e Nuno Severiano Teixeira. Rio de Mouro: Círculo de Leitores. Vol. 1, pp. 163-289.
• MORENO, Humberto Baquero (1973) — A Batalha de Alfarrobeira. Antecedentes e significado histórico. Lourenço Marques.
• MORENO, Humberto Baquero (1984) — «Uma carta do Cardeal Alpedrinha ao Príncipe D. João sobre a situação política da Itália em 1480». Revista da Faculdade de Letras. História. Porto. Vol. I, pp. 193-204.
• MOURE, Michel (1978) — «Espionnage». En Dictionnaire Encyclopedique D’Histoire. Bordas. Vol. 3, pp. 1642-1643.
• MOURE, Michel (1996) — «Espionnage». En Dictionnaire encyclopédique d’Histoire. Nouvelle édition. Poitiers: Larousse-Bordas. Vol. 4, p. 4114.
• PÉQUIGNOT, Stéphane (2017) — «Questions et débats : Espionnages». En Diplomatie et Relations Internationales au Moyen Âge (IXe-XVe siècle). Dir. Jean-Marie Moeglin. Paris : Press Universitaires de France, pp. 645-670.
• PINA, Rui de (1901) — Chronica d’El-Rei D. Affonso V. Lisboa: Escriptorio.
• PINA, Rui (1950) – Crónica de El-Rei D. João II. Prefácio e notas Alberto Martins de Carvalho. Coimbra: Atlântida.
• PINTO, Vítor Manuel da Silva Viana (2015) — De Olhar atento e Ouvidos à escuta… A espionagem militar na cronística portuguesa de Quatrocentos: Fernão Lopes e Gomes Eanes de Zurara. Coimbra: Faculdade de Letras da Universidade de Coimbra. Dissertação de mestrado.
• POWERS, James (1988) — A society organized for war. The Iberian municipal militias in the Central Middle Ages, 1000-1284. Berkeley-Los Angeles. London: University of California Press.
• REGO, A. da Silva Rego (1942) — «Duarte Castanho, espião e embaixador (1538-1542)». Anais da Academia Portuguesa de História. 2ª série. Vol. 4, pp. 131-250.
• RIBEIRO, Ângelo (1931) — « Alfarrobeira ». En História de Portugal. Dir. Damião Peres e Eleutério Cerdeira. Barcelos: Portucalense Editora, 1931. Vol. 3, pp. 87-100.
• SANTOS, João Marinho dos (1998) — A guerra e as guerras na Expansão portuguesa: séculos XV e XVI. Lisboa: Comissão Nacional para os Descobrimentos Portugueses.
• SENATORE, Francesco (1998) — «Uno mundo de carta». Forme e strutture della diplomazia sforzesca. Nápoles: Liguori Editore.
• SERRÃO, Joel [Dir.] (1985) — Dicionário de História de Portugal. Porto: Livraria Figueirinhas. 6 Vols.
• SOUSA, António Caetano de (1946-1955) — Provas da História Genealógica da Casa Real Portuguesa. Coimbra: Atlântida. Vol. 1.
• SOUSA, Armindo de (1993) — «A sociedade (estruturas, grupos e motivações). Eclesiásticos». En História de Portugal. A Monarquia Feudal (1096-1480). Dir. José Mattoso. Lisboa: Editorial Estampa. Vol. 2, pp. 423-440.
• SYLVAIN, Curtenaz (1988) — «Recensão crítica de ALEM, Jean-Pierre (1987) – L’espionnage: histoires, méthodes. Paris: La Vauzelle, 466 pp.» Revue Militaire Suisse. Nº 133, pp. 590-592.
• THOMAZ, Luís Filipe Reis (1994) — De Ceuta a Timor. Lisboa: DIFEL.
• VEGÉCIO, Flávio (2006) – Tratado de ciência militar. Lisboa: Edições Sílabo.
• ZURARA, Gomes Eanes de (1992) — Crónica da tomada de Ceuta, introdução e notas Reis Brasil. Lisboa: Europa-América.
• ZURARA, Gomes Eanes de (1997) — Crónica do Conde D. Pedro de Meneses. Edição e estudo de Maria Teresa Brocardo. Lisboa: FCG/JNICT.
• ZURARA, Gomes Eanes de (2006) — Crónica do Conde D. Duarte de Meneses. Edição diplomática de Larry King. Lisboa: Universidade Nova de Lisboa/Faculdade de Ciências Sociais e Humanas.

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