The war between the Plantagenets and the Valois for the throne of France is triggered by the death without heirs of Charles IV. The recovery by Philip VI of Valois of the Ponthieu from his English vassal caused devastation in East Picardy. After the French defeat at Crecy 1360, Ponthieu returned to England. Beauvaisis and Santerre are still controlled by the French, except during the 1429-1431 period when the Burgundians controlled northern Picardy and the English controlled southern Picardy. The English weaken and the war between Burgundy duke Philip the Good and French king Charles VII ends in 1435. However, the region remains disrupted until the late Middle Ages.