Historical conflicts between the Spanish and the French have shaped European history in interesting ways. The disputes involved not only the Basque communities on these countries' borders, but also control of Atlantic waters all the way to Spanish-American colonies up to important Newfoundland fisheries. The EU-funded Maritime Hegemony project closely investigated this phenomenon. It looked at how these conflicts led to the disintegration of Spanish maritime policy, instead ushering in the primacy of the French and the English in North America. Looking at peace treaties and legislation of the time, the project investigated the link between public and private warfare, examining the dynamics between local interests and international strategy as well. The monarchy, navy, role of commerce, fisheries and the economy were all affected by these developments. Through this investigation, the project aimed to understand how local communities exploited royal institutions and the military to fight for power against communities from other nations and further their interests. It also looked at how aware the Spanish court and monarchy were of this exploitation, juxtaposing its concerns for social, political and economic stability in border areas. The study focused on the second half of the 17th century, marked by two major events: the Treaty of the Pyrenees in 1659 and the reign of Louis XIV of France. Louis XIV abandoned the traditional role of judge king to assume one of warrior sovereign, with drastic impact on border communities and cross-border relations. Aspects of absolutist politics, sovereignty and obedience all came into play here. In-depth research in Spanish, French and British libraries, combined with insights from experts, helped shed light on the global dynamics in times of conflict. With history often repeating itself and a world that continues its disputes, investigating this phenomenon over the long term could help improve policymaking and promote peace.