Chivalry and Betrayal: The Hundred Years' War
In 1435 Bedford died and sworn enemies Charles VII and Phillip, Duke of Burgundy joined forces to get the English out and with Henry VI reluctance to wage war and to maintain peace by marrying Margaret of Anjou. Charles had no intention of peace and used cannon and sieges to retake France and Normandy culminating in the defeat of the English at the Battle of Castillon in the last English territory of Gascony ending the hundred years war.
Duchy of Aquitaine
The Valois kings of France, claiming supremacy over Aquitaine, granted the title of duke to their heirs, the Dauphins, during 1345 and 1415: John II (1345–50), Charles VII (1392?–1401), and Louis (1401–15). French victory was complete with the Battle of Castillon of 1453. England and France nominally remained at war for another 20 years, but England was in no position to continue its campaign, due to its escalating internal conflicts. The Hundred Years' War was formally concluded with the Treaty of Picquigny of 1475. With the end of the Hundred Years' War, Aquitaine returned under direct rule of the king of France and remained in the possession of the king. Only occasionally was the title of "duke of Aquitaine" granted to another member of the dynasty, and then as a purely nominal distinction.