When Mary was born at
Bishop's Waltham Palace,
Hampshire, on 10 October 1344, her future husband was already living with her brothers and sisters in the royal nursery. 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. After the lifting of the siege, she visited England in 1342 and left John with Edward for safety. He was assigned apartments in the royal nursery while his mother returned to France. Since Mary had been considered betrothed to John since birth, she was now, at the age of one, titular Duchess of Brittany. Mary and John spent their childhood together at
The Tower,
Langley,
Eltham,
Woodstock, Sunning,
Clarendon and other royal palaces. There is only one record of Mary ever leaving the court household and that was to visit her brother
John of Gaunt and his wife
Blanche, who had just had their first child. However, this visit was cut short by the death from plague of her uncle,
Henry Duke of Lancaster, on 25 March 1361. Mary and her younger sister Margaret were only allowed very limited visits to family and were given less pocket money (20 marks per year) than their older siblings. Her situation did not change after marriage since she and her husband remained at the English court. Further arrangements were planned for when the couple would leave England and take up residence in Brittany as the recognised Duke and Duchess. However, within a few months, Mary developed "a lethargic disease from which it was impossible to rouse her" Her husband referred to her as "my late dearest companion". ==Notes==