Louis IX claimed feudal overlordship over the counties of the Hispanic March, as heir of Charlemagne. James I of Aragon, king of Aragon, Majorca and Valencia, count of Barcelona and Urgell and lord of Montpellier, claimed rights in Languedoc. The instrument of peace was signed on 11 May 1258, at the priory of Saint-Jean-en-l'Isle in Corbeil, today Corbeil-Essonnes. For France, the king in person. For Aragon, three procurators: Arnau de Gurb, bishop of Barcelona; Guillaume, prior of Sainte-Marie de Corneilla; Guillaume de Roquefeuil, the king's lieutenant in Montpellier. They produced procuratorial letters sealed by James.

Louis, for himself and his successors, quitclaimed all right and possession he claimed in the counties of Barcelona, Urgell, Besalu, Roussillon, Emporda, Cerdanya, Conflent, Girona and Osona, with honours, homages, districts and jurisdictions. He promised to reclaim nothing there and to hand James any old charter on the subject. The southern border of the French crown stopped, in practice, at the Pyrenees.

The procurators, in James's name, ceded all right over Carcassonne and the Carcasses, Razes, Lauragais, Termes, Beziers, Agde, Albi, Rouergue, Narbonne, the Minervois, Fenouillet and the Fenouilledes, the land of Sault, Peyrepertuse and the Peyrepertuses, Millau, Gevaudan, Nimes, Toulouse with Saint-Gilles. James kept the lordship of Montpellier, the viscounty of Carlat and the barony of Aumelas.

The May text also listed the county of Foix. James ratified on 16 July 1258, but refused Foix: it was not, he said, under the overlordship of the king of France. The treaty provided that James's daughter Isabella would marry Philip, son of Louis, the future Philip III. The next day, 17 July, James ceded his hereditary rights to the county of Provence, an imperial fief, to Margaret, wife of Louis and daughter of Ramon Berenguer IV, count of Provence.

The sequel: the House of Barcelona withdrew from Languedoc politics; the cultural and economic ties between Catalonia and Occitania faded by degrees. Provence could later pass to the Capetian house of Anjou. This is not another Treaty of Corbeil. The cover is Jaume Mateu's portrait of James I; Guillaume de Roquefeuil's seal is a gif, and Louis IX on Commons is too small.

Sources: Treaty of Corbeil (1258); Instrumentum de pace inter Ludovicum et Jacobum.