A band of brothers? Capetian princes in Anglo–French diplomacy, 1230s–1260s

Abstract Robert of Artois, Alphonse of Poitiers and Charles of Anjou spent their lives within the inner circles of power of their brother, King Louis IX (1214–70). Princes of a realm where the upper aristocracy no longer automatically shared in governmental decision-making, the king’s brothers also controlled new apanages that did not challenge the inalienability of the kingdom, and they enjoyed a particularly strong position close to the king. This article examines the political roles and cohesion of this group of brothers, who have frequently been presented in historiography as a strong family unit. It focuses upon their diplomatic activities, which gave them greater visibility as the king’s representatives, and which allow us to assess the distinctive nature of their roles. Comparisons with the Plantagenet dynasty during the reign of King Henry III (1216–71) highlight just how much Louis IX relied on blood ties yet simultaneously forced his brothers to remain in the background when he was shaping policy.