Rhys and his brother Goronwy were rhaglaws for the commote of Dindaethwy across three decades; from the 1370s through to the 1390s. He was made Sheriff of Anglesey twice, first between 1374–75 and again in 1381-84. This was a post more typically held by an Englishman at the time. In 1386, Rhys was one of the leaders of a contingent of soldiers raised in Caernarfonshire to protect against a potential invasion by the French. 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. However, that same year Rhys was summoned before the king's justicar of North Wales to explain why he had managed to become indebted to the sum of £60 in his role of rhaglaw at Dindaethwy. Rhys held lands in Anglesey and Caernarfonshire which he inherited from his father, and these would have provided a steady income.
Revolt
In September 1399, King Richard II was overthrown by Henry IV. When Rhys' cousin Owain Glyndŵr began a rebellion the following year, he and his brothers publicly backed him. While Owain's rebellion in North East Wales faltered, Rhys and his family rose up against the king on Anglesey. Henry IV personally took an army to put down the revolt, and harried the island, burning the FranciscanLlanfaes Friary near Bangor, Gwynedd, where the Tudur family were buried. Rhys led troops to ambush them from an advantageous spot on Rhos Fawr. When he engaged Henry's troops, the English fled to the safety of Beaumaris Castle. When Henry issued a general pardon for those of North Wales in March 1401, he purposely excluded Rhys, his brother Gwilym and Owain Glyndŵr. As a result, Rhys and Gwilym hatched an audacious plan. On Good Friday, 1 April 1401, the brothers and 44 men infiltrated Conway Castle. They pretended to be carpenters, and entered the castle while the guard were in church, capturing it. Negotiations began for the return of the castle on 13 April, with the king represented by Henry "Hotspur" Percy. After seeking a compromise, which would have resulted in pardons being given to the Welshmen, the king overrode Percy's decision on 20 April. An agreement was finally reached on 24 June after several failed attempts when Gwilym began writing to the king directly. Percy subsequently liaised with Rhys in preparation for his own rebellion against the king on 1403, which started and ended with the Battle of Shrewsbury where Percy was killed by the king's forces. All three Tudur brothers were outlawed by the king in 1406. The constable of Welshpool Council arrested several rebel leaders, including Rhys and transported him to Chester. Documents from the era show that Rhys was executed there in 1412.
Legacy
After the execution of Rhys, his brother Gwilym was given a full pardon a year later. Both their lands had been forfeited when they joined with Owain's rebellion and passed to Gwilym ap Gruffydd, who had married Morfudd, the daughter of Goronwy ap Tudur. Rhys' death was later lamented in a poem by Gruffydd Gryg.
