Urban Diplomacy and Criminalization of Piracy in Southwestern Atlantic Europe in the Late Middle Ages

War dominated the royal policies in late Medieval Europe, yet recent historiography has shifted focus to the conflict resolution strategies employed by nonsovereign powers. This essay delves into the escalation of confrontations at sea, distinguishing between legal acts of privateering and criminal acts of piracy. It further compares the conflict mitigation policies of the town ports of Northern Iberia and the duchy of Brittany, highlighting the role of an international arbitration court, the Guild of the Contractation. The analysis concludes that attempts to diminish maritime violence through shortlived bilateral peace agreements were largely unsuccessful, with the more stringent policies of monarchical states taking precedence. Despite this, trade and maritime transport remained crucial for the inhabitants of both regions, who endeavored to surmount the perils of the sea by fostering networks of trust, bolstered by shared institutions for risk management. Nevertheless, these efforts were ultimately eclipsed by the royal policies aimed at extending state jurisdiction over the seas, through the criminalization of certain sea activities, thereby reinforcing the states control over maritime commerce. The essay underscores the complex interplay between local interests and royal ambitions, illustrating how the latter often subsumed the former in the quest for greater control over maritime resources and trade routes.