 It took place in 1083 in the castle of Rueda de Jalón, when Alfonso VI received news that the governor of that stronghold, which belonged to the Taifa of Zaragoza, intended to surrender it to the Leonese king.The king's troops were ambushed when they entered the castle and several of the most important magnates of the kingdom were killed.In 1074, Alfonso VI's vassal and friend Al-Mamun, king of the Taifa of Toledo died of poisoning in Córdoba, and was succeeded by his grandson Al-Qádir, who asked for help from the Leonese monarch to end an uprising against him.