In 1401 Rhys ap Tudur and his brother Gwilym successfully captured the castle by posing as carpenters, killing the watchmen on duty, and opening the gates. They held the castle for 3 months before negotiating a surrender with Henry IV.
In the Historia Brittonum written in the the early 9th century, Nennius mentions that a tomb with the inscription "Constantius the Emperor" still stood at the site. Some believe it was the tomb Constantius, father of Constantine the Great. Others believe it could be the tomb of Constantine (not that one) son of Magnus Maximus and Saint Helen.
