Battle of Castillon
England's ally Philip III, Duke of Burgundy defected to Charles, when the English ambassadors' refusal to renounce the claim to the French crown stalled negotiations, signing the Treaty of Arras (1435). The French reorganised the superior numbers of their feudal levies into a modern professional army and retook Paris, Rouen, Bordeaux and Normandy. Victories at the Battle of Formigny in 1450 and the Battle of Castillon in 1453 brought the war to an end with the House of Lancaster losing forever all its French holdings, except Calais and the Channel Islands.