Hundred Years' War (1415–53)
The Lancastrian War was the third and final phase of the Anglo-French Hundred Years' War. It lasted from 1415, when King Henry V of England invaded Normandy, to 1453, when the English lost Bordeaux. It followed a long period of peace from the end of the Caroline War in 1389. The phase was named after the House of Lancaster, the ruling house of the Kingdom of England, to which Henry V belonged.
Mary of Waltham
Seven years previously, King Philip VI of France attempted to confiscate the Duchy of Guyenne (also referred to as Aquitaine) from Edward III – an event that traditionally marks the beginning of the Hundred Years' War – after which Edward used military force, diplomacy and marital links to strengthen his claim to the French throne. In the Duchy of Brittany succession dispute, he supported John of Montfort since a close alliance to the English crown with Brittany would give Edward access to the port of Brest for use by English troops. When Montfort was captured, his wife, Joanna of Flanders, took over the campaign and, during the siege of Rennes, received military support from Edward. In return, she promised her son John (later John IV, Duke of Brittany) to one of his daughters.