Recovery began with the reestablishment of the duchy of Aquitaine in the mid-10th
century, when the dynasty of the counts of Poitiers, in the far northern part of the
province, gained possession of the ducal title. Successive descendants, all named
William, ruled the duchy for nearly two centuries until extinction of the male line at the
death of William X in 1137. Under the Poitevin count-dukes, the duchy of Aquitaine
became one of the greatest territorial principalities in France, reaching its high point in
power and prestige under the rule of William V the Great (r. 995–1030) and Guy-
Geoffrey (William VIII, r. 1058–86). The latter completed the unification of the
previously independent duchy of Gascony with Aquitaine in 1058 and thereby made his
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