King Alfonso of Aragon and of Navarre,…

King Alfonso of Aragon and of Navarre, called “the Battler” for his efforts against the Moors in southern Spain, had in 1109 married Castile’s ambitious and passionate heiress Urraca, widow of Raymond of Burgundy, at the behest of her father, Alfonso VI, King of León and Castile.

The four Christian kingdoms of Spain are thus nominally united against the Muslim Almoravid Empire and Alfonso I takes his father-in-law's imperial title—Imperator totius Hispaniae—at his death later in the year, but the union fails because Leon and Castile feel hostility toward an Aragonese emperor; because Urraca dislikes her second husband; and because Bernard, the French Cluniac archbishop of Toledo, wants to see his protégé, Alfonso Ramírez (infant son of Urraca and her Burgundian first husband), on the imperial throne.

The nobles of the two kingdoms have taken up their monarchs’ enmity, resulting in battles between Alfonso’s troops and those loyal to Urraca, her family, and Castilian partisans.

Alfonso had been victorious at the Battle of Sepulveda in 1111, but the Aragonese-Castilian War continues with minor skirmishing until he accepts the dissolution of the marriage, by papal decree (as they are second cousins), and of the political union, in 1112.

(Alfonso returns to Aragon but will continue to be involved in civil strife in the central kingdom until he eventually abandons his claims in favor of his stepson after the death of Urraca in 1126.)