Background
Rhys was the fourth son of Rhys ap Gruffydd (The Lord Rhys) and his wife Gwenllian, daughter of Madog ap Maredudd of Powys. He married Mathilde, the daughter of Richard de Clare, 3rd Earl of Hertford.
Rhys was the fourth son of Rhys ap Gruffydd (The Lord Rhys) and his wife Gwenllian, daughter of Madog ap Maredudd of Powys. He married Mathilde, the daughter of Richard de Clare, 3rd Earl of Hertford.
Their father however retaliated by capturing both of them and imprisoning them in Ystrad Meurig Castle. Rhys Gryg reappears in 1204. In 1204 Rhys made an alliance with Gruffydd"s sons, Rhys and Owain, and drove Maelgwn out of Ystrad Tywi which was then shared between them, with Rhys Gryg getting the Cantref Mawr.
However, when King John built a castle at Aberystwyth, Rhys and Maelgwn changed sides, attacked the castle and burnt lieutenant
In 1212 Rhys attacked and burnt Swansea. The sons of Gruffydd ap Rhys, Rhys and Owain, had now made their peace with King John and gone over to the English Royal side.
Later in the year he was captured by the English and imprisoned at Carmarthen. At the parliament held by Llywelyn at Aberdovey in 1216, Rhys Gryg was allocated Cantref Mawr and Cantref Bychan and other lands.
Rhys supported Llywelyn during the remainder of his career.
In 1234 he joined with Maelgwn Fychan again to attack Carmarthen, but received wounds of which he died at Llandeilo Fawr shortly afterwards. The ancient arms of the House of Dinefwr Gules, a lion rampant or within a bordure or were inherited and assumed in lieu of the Talbot paternal arms as "arms of alliance" on marriage to a great princess.