Hackney Family Tree

https://en.wikipedia.org/wiki/Eleanor_of_Castile#Marriage

In 1252, Alfonso X had resurrected another ancestral claim, this time to the duchy of Gascony, in the south of Aquitaine, 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 1254 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, 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 before the wedding took place.

The young couple were married at the monastery of Las Huelgas, Burgos, on 1 November 1254. Edward and Eleanor were second cousins once removed, as Edward's grandfather King John of England and Eleanor's great-grandmother Eleanor of England were the son and daughter of King Henry II and Eleanor of Aquitaine. Following the marriage they spent nearly a year in Gascony, with Edward ruling as lord of Aquitaine. During this time Eleanor, aged thirteen and a half, almost certainly gave birth to her first child, a short lived daughter[citation needed]. She journeyed to England alone in late summer of 1255. Edward followed her a few months later.[5]

Henry III took pride in resolving the Gascon crisis so decisively, but his English subjects feared that the marriage would bring Eleanor's kinfolk and countrymen to live off Henry's ruinous generosity. A few of her relatives did come to England soon after her marriage. She was too young to stop them or prevent Henry III from supporting them, but she was blamed anyway and her marriage soon became unpopular. Eleanor's mother had been spurned in marriage by Henry III and her great-grandmother, Alys of France, Countess of Vexin, had been spurned in marriage by Richard I of England.

However, the presence of more English, French and Norman soldiers of fortune and opportunists in the recently reconquered Seville and Cordoba Moorish Kingdoms would be increased, thanks to this alliance between royal houses, until the advent of the later Hundred Years War when it would be symptomatic of extended hostilities between the French and the English for peninsular support.