A Border Policy? Louis IX and the Spanish Connection

It has long been recognized that King Louis IX of France (1226-1270) was committed to trying to maintain peace among Christian powers in Europe both for psychological/ideological reasons, his well-documented desire to fulfill the image of the peacemaking king, and for strategic reasons, namely, his desire, also well-documented, to marshal the resources of the Christian states for their wars with Islamic polities.  Two aspects of his peace initiatives have received considerable attention: his peace treaties with England and Aragon and his role as an arbiter in other disputes in Europe.  One other aspect of his initiatives requires more investigation than it has so far received.  This is the relation of his border policies, suggested in the treaties, with other manifestations of his concerns about border principalities.  This paper explores this theme with regard to France and the Spanish kingdoms.