 Thomas was executed, and the castle became the property of the Crown before passing into the Duchy of Lancaster.Dunstanburgh's defences were expanded in the 1380s by John of Gaunt, the Duke of Lancaster, in the light of the threat from Scotland and the peasant uprisings of 1381.The castle was maintained in the 15th century by the Crown, and formed a strategic northern stronghold in the region during the Wars of the Roses, changing hands between the rival Lancastrian and Yorkist factions several times.