The Duchy of Aquitaine (Occitan: Ducat d'Aquitània, IPA: [dyˈkad dakiˈtanjɔ]; French: Duché d'Aquitaine, IPA: [dyʃe dakitɛn]) was a historical fiefdom located in the western, central, and southern areas of present-day France, south of the river Loire. The full extent of the duchy, as well as its name, fluctuated greatly over the centuries and at times comprised much of what is now southwestern (including Gascony) and central France.
The territory originated in 507 as a constituent kingdom of Francia after the Salian Franks conquered Aquitaine following the Battle of Vouillé; its boundaries were ultimately a combination of the Roman provinces of Aquitania Prima and Secunda. As a duchy, it broke up after the conquest of the independent Aquitanian duchy of Waiofar, going on to become a sub-kingdom within the Carolingian Empire. It was then absorbed by West Francia after the partition of Verdun in 843 and soon reappeared as a duchy under West Francia. In 1153, an enlarged Aquitaine pledged loyalty to the Angevin kings of England. As a result, a rivalry emerged between the French monarchs and the Angevins over control of the latter's territorial possessions in France. By the mid-13th century, only an enlarged Guyenne and Gascony remained in Angevin hands. The Hundred Years' War finally saw the Kingdom of France gain full control over Aquitaine in the 1450s, with much of its territory directly incorporated into the French royal domain itself.