Career
The castle was besieged by an English force under the command of William de Valance on 15 April. On 21 April his men were supplemented by those of Roger Lestrange. On the following day, the pair negotiated for the surrender of the castle by Cynfrig, offering £80 if the defenders yielded within a week.
He seemingly agreed, for the castle was surrendered on 25 April and a payment of £53 made, but the prince of Wales, Dafydd ap Gruffudd, was not in lieutenant
He apparently escaped during the siege, and was not captured until 22 June. There are no further references to Cynfrig.
The siege over which he presided was the longest of a native Welsh castle during the war.
