In 1401, he and his brother Gwilym ap Tudur took Conwy Castle after infiltrating it, and liaised with Henry Percy prior to his own rebellion in 1403.
After being outlawed by the king in 1406, Rhys was captured and executed at Chester in 1412, although later oral tradition claims he returned to Anglesey to die there.
[1] Tudur had served with the forces of King Edward III of England during the campaigns in France in 1337, assuming the rank of knight in the process.
King Richard II of England paid Rhys £10 a year to retain his service should the crown require it, and accompanied him on a military expedition to Ireland in 1398.
[4] However, that same year Rhys was summoned before the king's justiciar of North Wales to explain why he had managed to become indebted to the sum of £60 in his role of rhaglaw at Dindaethwy.
Henry IV personally took an army to put down the revolt, and harried the island, burning the Franciscan Llanfaes Friary near Bangor, Gwynedd, where the Tudur family were buried.
[5] When Henry issued a general pardon for those of North Wales in March 1401, he purposely excluded Rhys, his brother Gwilym and Owain Glyndŵr.