Henry VI's reign also saw England's defeat in the Hundred Year's War. England had done well in the war while he was still a child, and by 1428, the English appeared to be close to defeating their House of Valois enemies. However, they soon had problems, including Joan of Arc's rebellions in 1429-1430 and Burgundy's decision to switch sides in 1435. Because of these problems, England's control in France was already weakened when Henry VI started to run the government in 1437. Henry VI tried to end the war with a peace agreement, but his French enemies realised that they could win a complete victory. In 1453, England had lost all their lands in France apart from Calais.