The market is first mentioned in 1206 and the fair in 1304 but the earliest known charter was granted by Edward II in 1310, confirming Wednesday as Market Day and the fair to be held between July 18th and July 20th.
During this time the castle continued to expand. Under Edward II it gained twelve towers and a keep.
Rebels occupied the castle during Edward’s reign and the curtain wall was breached with a siege engine during its recapture. Later, Scots invaders burned much of the town, including the parish church. The church was restored by Queen Philippa, wife of Edward III, who had been granted “the Castle, Town, Forest and Honour of Knaresborough” as part of her marriage settlement in 1328. After her death the Honour was granted in 1372 by Edward to their youngest son, John of Gaunt (born in Ghent). He had already inherited the estates of his wife, Blanche of Lancaster, and was Duke of Lancaster and thus linked the Honour of Knaresborough with the Duchy of Lancashire and hence to the Lancastrian cause in the Wars of the Roses.
King Richard II spent a night in Knaresborough Castle on his way to Pontefract Castle in 1399 where he was murdered.