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, they English appeared to be close to defeating their House of Valois enemies. However, Joan of Arc's rebellions in 1429-1430 was one reason for Burgundy's decision to switch sides in 1435. Several other problems made England's control in France to be already weakened when Henry VI started to run the government in 1437.