Aquitaine

Aquitaine was one of the three divisions of classical Gaul. After the end of Roman rule it feel first to the Visigoths and then later, in c.507CE, to the Franks.

Around 725 CE it was raided by Muslims coming from Spain. Charles Martel defeated the invaders and brought Aquitaine into the Carolingian empire.

In the 9th century the counts and other nobility of the region sought to excuse themselves from royal control; their nascent duchy, however, foundered, and it was William V who successfully founded a dynasty, as duke, basing himself in Poitou.
When William X died, his daughter, Eleanor married the kign of France, Louis VII, but their marriage was unsuccessful and, after divorce in 1152CE, she re-married, to Louis' rival, the English king, Henry II, bringing Aquitaine as her dowry, and making the kings of England the feudal subjects, as Dukes of Aquitaine, of the French crown.
In 1224 the French king conquered Poitou; thereafter the French whittled away at Aquitaine, justified by the reluctance (and on occasions refusal) of the English to obey their royal overlord. In the 1360s', the English king Edward III managed temporarity to reconstitute Aquitaine, as a result of victories during the Hundred Years War, but the French fought back and finally overran the last vestiges of English control in 1453.