In 1170 Eleanor married King Alfonso VIII of Castile in Burgos.
Her parents' purpose in arranging the marriage was to secure Aquitaine's Pyrenean border, while Alfonso was seeking an ally in his struggles with Sancho VI of Navarre.
 In 1177, this led to Henry overseeing arbitration of the border dispute.

Around the year 1200, Alfonso began to claim that the duchy of Gascony was part of Eleanor's dowry, but there is no documented foundation for that claim.
 It is highly unlikely that Henry II would have parted with so significant a portion of his domains.
At most, Gascony may have been pledged as security for the full payment of his daughter's dowry.
Her husband went so far on this claim as to invade Gascony in her name in 1205.
 In 1206, her brother John granted her safe passage to visit him, perhaps to try opening peace negotiations.
 In 1208, Alfonso yielded on the claim.
 Decades later, their great-grandson Alfonso X of Castile would claim the duchy on the grounds that her dowry had never been fully paid.

Of all Eleanor of Aquitaine's daughters, her namesake was the only one who was enabled, by political circumstances, to wield the kind of influence her mother had exercised.
In her own marriage treaty, and in the first marriage treaty for her daughter Berengaria, Eleanor was given direct control of many lands, towns, and castles throughout the kingdom.
She was almost as powerful as Alfonso, who specified in his will in 1204 that she was to rule alongside their son in the event of his death, including taking responsibility for paying his debts and executing his will.
It was she who persuaded him to marry their daughter Berengaria to Alfonso IX of León.
Troubadours and sages were regularly present in Alfonso VIII's court due to Eleanor's patronage.

Eleanor took particular interest in supporting religious institutions.
 In 1179, she took responsibility to support and maintain a shrine to St. Thomas Becket in the cathedral of Toledo.
 She also created and supported the Abbey of Santa María la Real de Las Huelgas, which served as a refuge and tomb for her family for generations, and its affiliated hospital.

When Alfonso died, Eleanor was reportedly so devastated with grief that she was unable to preside over the burial.
Their eldest daughter Berengaria instead performed these honours.
Eleanor then became sick and died only twenty-six days after her husband, and was buried at Abbey of Santa María la Real de Las Huelgas.
In 1170 Eleanor married King Alfonso VIII of Castile in Burgos. Her parents' purpose in arranging the marriage was to secure Aquitaine's Pyrenean border, while Alfonso was seeking an ally in his struggles with Sancho VI of Navarre.  In 1177, this led to Henry overseeing arbitration of the border dispute.
Around the year 1200, Alfonso began to claim that the duchy of Gascony was part of Eleanor's dowry, but there is no documented foundation for that claim.  It is highly unlikely that Henry II would have parted with so significant a portion of his domains. At most, Gascony may have been pledged as security for the full payment of his daughter's dowry. Her husband went so far on this claim as to invade Gascony in her name in 1205.  In 1206, her brother John granted her safe passage to visit him, perhaps to try opening peace negotiations.  In 1208, Alfonso yielded on the claim.  Decades later, their great-grandson Alfonso X of Castile would claim the duchy on the grounds that her dowry had never been fully paid.
Of all Eleanor of Aquitaine's daughters, her namesake was the only one who was enabled, by political circumstances, to wield the kind of influence her mother had exercised. In her own marriage treaty, and in the first marriage treaty for her daughter Berengaria, Eleanor was given direct control of many lands, towns, and castles throughout the kingdom. She was almost as powerful as Alfonso, who specified in his will in 1204 that she was to rule alongside their son in the event of his death, including taking responsibility for paying his debts and executing his will. It was she who persuaded him to marry their daughter Berengaria to Alfonso IX of León. Troubadours and sages were regularly present in Alfonso VIII's court due to Eleanor's patronage.
Eleanor took particular interest in supporting religious institutions.  In 1179, she took responsibility to support and maintain a shrine to St. Thomas Becket in the cathedral of Toledo.  She also created and supported the Abbey of Santa María la Real de Las Huelgas, which served as a refuge and tomb for her family for generations, and its affiliated hospital.
When Alfonso died, Eleanor was reportedly so devastated with grief that she was unable to preside over the burial. Their eldest daughter Berengaria instead performed these honours. Eleanor then became sick and died only twenty-six days after her husband, and was buried at Abbey of Santa María la Real de Las Huelgas.
Eleanor of England, Queen of Castile