The ‘de Grey’ family remained at Ruthin Castle until 1508. They had clung on to their domain through various upsets and throughout the War of the Roses. They were military experts and men of outstanding ability in the affairs of state. They were valued by both the houses of Lancaster and York but towards the end of the 14th century, Reginald, the 3rd Baron of Ruthin, came into conflict with a neighbour over the right to a piece of land at Croesau (known now as Bryn Eglwys).
The Welsh had been loyal and content during the reign of King Richard II but after he left the throne, fresh disturbances broke out. Both Reginald de Grey and Owain Glyndwr had served Richard well and both were well thought of by Henry IV but a crisis was looming. Henry IV resumed war with Scotland and to raise an army, he issued writs to all his Barons. The task of passing the said writ to Owain fell upon Reginald, who decided not to give it to him, thus putting Owain in bad favour with the King. Reginald’s plan for gaining Owain’s land was thus put into action whilst Owain presumed that he had been slighted by the King. Soon after this a minor revolt grew quickly and Owain guessed that it was Reginald behind it and set out to plunder Reginald’s land.
On the 18 September 1400, during the preparation for the great fair on St. Matthews Day (21 September), Owain hit the town of Ruthin in a furious attack. His men looted and burned the town down but were unable to take the castle. It wasn’t until 2 years later at a place called Bryn Saith Marchog, that Owain caught Reginald in an ambush and took him captive and placed a hefty ransom upon his head of 10,000 marks. The terms were very stiff but King Henry VII agreed to them on behalf of the de Grey’s. The de Grey’s never fully recovered from the severe loss inflicted by the heavy ransom.