Unsettled Borders: The Treaty of Alcañices (1297), its Contestation Process in 1312, and its Consequences. A New Perspective

The frontier between two kingdoms was, during the medieval period, and even today, a complex matter to solve. The political pretensions, economic-strategical interests, and the resources available meant, in many cases, that negotiations and demarcations on the terrain had a direct impact locally but also, especially in this case, internationally. The Treaty of Alcañices was a diplomatic agreement signed between the kingdoms of Castile and Portugal in 1297. To Castile, it served, primarily, as a peace treaty which ensured the welfare of the kingdom that was dealing with a domestic crisis. To Portugal, it was above all a boundary treaty which set out and delimited the territory of jurisdiction. This was an essential agreement for the Portuguese as it defined the ultimate boundaries of Portugal, which mostly prevail to this day. Nevertheless, while crucial for peacekeeping, it wasn't easy to comply with the resolutions stipulated in the negotiated agreements, particularly when these had a direct impact on the boundaries of a territory. A good illustration of this situation, which is the focus of this article, and a less studied event, was that, in 1312, this same treaty was contested by the very same King of Castile that had signed it years earlier. With the intervention of the King of Aragon, who was seeking to profit and assure his own interests by mediating of the diplomatic issue, Fernando IV of Castile advocated the nullity of the established diplomatic treaty, thus calling into question its resolutions and, consequently, the frontier line defined between these two kingdoms. In view of the documentation that is mainly preserved at the Archivo de la Corona de Aragón (Barcelona), we aim to scrutinise both the diplomatic events and processes, as well as the long-term consequences of this dispute.