Hostilities between the counts of Anjou and Blois were renewed in 1016. During the course of the conflict, Fulk lost control of three castles: Passavant was destroyed and Montbazon and Langeais were probably captured. By 1032 Château de Langeais was back under Fulk's control. However it was again taken by the forces of Odo II, Count of Blois.
Alan II was also allied to Theobald I of Blois, the count of Chartres. Alan II had married Theobald's sister, Adelaide, giving Theobald influence all the way to Rennes. However Alan II's death left a void in Brittany leaving it vulnerable to encroachment by either the Normans or the Angevins.