Gwilym ap Tudur Rhys and Owain Glyndŵr. As a result, the Tudur brothers began planning an attack on Conway Castle. On Good Friday, 1 April 1401, the brothers and 44 men (which included those who had also been excluded from the pardons) infiltrated the castle. They had pretended to be carpenters, and captured the castle while the guard were in church. Negotiations began for the return of the castle on 13 April, with the king represented by Henry "Hotspur" Percy and Gwilym representing the Welsh forces. After seeking a compromise, which would have resulted in pardons being given to the Welshmen, the king
Grosmont Castle was during the revolt of Owain Glyndŵr at the start of the 15th century. There was a battle between the Welsh and Richard Beauchamp, 13th Earl of Warwick near Grosmont in 1404, leading to an English victory. The castle was besieged the next year by Owain's son, Gruffudd, but the castle was relieved by an English force sent by Prince Henry. By 1538, Grosmont Castle had fallen into disuse and then into ruin; a 1563 survey notes that its bridge had collapsed and that, although the outer walls were intact, the interior was in decay and its building materials inside