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.
House of Valois
Because diplomacy and negotiation had failed, Edward III would have to back his claims with force to obtain the French throne. For a few years, England and France maintained an uneasy peace. Eventually, an escalation of conflict between the two kings led to the confiscation of the duchy of Aquitaine (1337). Instead of paying homage to the French king, as his ancestors had done, Edward claimed that he was the rightful King of France. These events helped launch the Hundred Years' War (1337-1453) between England and France. Though England failed to win that prolonged conflict, English and British Monarchs until the late 18th Century continued to maintain, at least formally, a claim to the French throne.