In 1252, Alfonso X resurrected another ancestral claim, this time to the duchy of Gascony in the south of Aquitaine (the last possession of the Kings of England in France), which he claimed had formed part of the dowry of Eleanor of England. Henry III of England swiftly countered Alfonso's claims with both diplomatic and military moves. Early in 1253, the two kings began to negotiate; after haggling over the financial provision for Eleanor, Henry and Alfonso agreed she would marry Henry's son Edward (by now the titular duke), and Alfonso would transfer his Gascon claims to Edward. Henry was so anxious for the marriage to take place that he willingly abandoned elaborate preparations already made for Edward's knighting in England and agreed that Alfonso would knight Edward on or before the next Feast of Assumption.
