In 1163 he formed an alliance with Rhys ap Gruffydd of Deheubarth to challenge English rule.

Plaid Genedlaethol Cymru () was formed on 5 August 1925, by Moses Gruffydd, Fred Jones and Lewis Valentine, members of (); and H. R. Jones, Saunders Lewis and David John Williams of Y Mudiad Cymreig ().

There was a general Welsh revolt against the Normans in 1136, following the death of Henry I, and Gruffydd formed an alliance with Gwynedd.

Owain and Cadwaladr, in alliance with Gruffydd ap Rhys of Deheubarth, won a major victory over the Normans at Crug Mawr near Cardigan in 1136 and annexed Ceredigion to their father's realm.

The Welsh Marcher Lords particularly resented Montfort's alliance with Llywelyn ap Gruffydd, Prince of Wales.

These were the paternal arms of Gwenllian, the daughter and heiress of Rhys Mechyll ( d. 1244 ) Prince of the Welsh House of Dinefwr, grandson of Rhys ap Gruffydd, and wife of Gilbert Talbot ( d. 1274 ), grandfather of Baron Talbot | Gilbert Talbot, 1st Baron Talbot ( d. 1345 / 6 ) assumed by Talbot as arms of alliance of a great heiress, superseding his own former paternal arms of Bendy of 10 pieces argent and gules

Shortly after the Battle of Mynydd Carn in 1081, Gruffydd was lured into a trap with the promise of an alliance but seized by Hugh the Fat, 1st Earl of Chester in an ambush near Corwen Earl Hugh claimed the Perfeddwlad up to the Clwyd river ( the commotes of Tegeingl and Rhufoniog ; the modern counties of Denbighshire Flintshire and Wrexham ) as part of Chester, and viewed the restoration of the Aberffraw family in Gwynedd as a threat to his own expansion into Wales.

Rhys however made an alliance with Gruffydd ap Cynan who was seeking to regain the throne of the Kingdom of Gwynedd, and at the Battle of Mynydd Carn in the same year they defeated and killed Caradog ap Gruffydd and his allies Trahaearn ap Caradog of Gwynedd and Meilyr ap Rhiwallon.

In alliance with Gruffydd ap Rhys of Deheubarth, he won a crushing victory over the Normans at the Battle of Crug Mawr, just outside Cardigan.

Trahaearn ruled Gwynedd until 1081, when Gruffydd ap Cynan returned from Ireland with an army of Danes and Irish and made an alliance with Rhys ap Tewdwr who had recently been ousted as prince of Deheubarth by Caradog ap Gruffydd of Morgannwg.

Trahaearn countered by making an alliance with Caradog ap Gruffydd.

As administrator of the Diocese of Hereford, he was involved in fighting against the Welsh, suffering two defeats at the hands of raiders before securing a settlement with Gruffydd ap Llywelyn, a Welsh ruler.

As recently as 1049 Irish raiders had allied with Gruffydd ap Rhydderch of Gwent in raiding along the River Usk.

Quickly Owain dispatched Gruffydd Young and his brother-in-law, John Hanmer, to negotiate with the French.

In his later years Rhys had trouble keeping control of his sons, particularly Maelgwn and Gruffydd, who maintained a feud with each other.

* Viking Irish raiders ally with Gruffydd ap Rhydderch of Gwent in raiding along the River Usk.

* Rhys ap Gruffydd agrees to negotiate with Henry II of England.

In 1055 Gruffydd ap Llywelyn established himself as the ruler of all Wales, and allied himself with Ælfgar of Mercia, who had been outlawed for treason.

In 1056, the area was devastated by the Welsh prince Gruffydd ap Llywelyn, on his way with an army of Welsh, Saxons and Danes to defeat Ralph, Earl of Hereford and sack the Saxon burh at Hereford, to the north.

His son, Owain Gwynedd, allied with Gruffydd ap Rhys of Deheubarth won a crushing victory over the Normans at the Battle of Crug Mawr in 1136 and annexed Ceredigion.

When John was forced to sign Magna Carta, Llywelyn was rewarded with several favourable provisions relating to Wales, including the release of his son Gruffydd who had been a hostage since 1211.

The " brilliant but wayward " Gruffydd was a favorite with Welsh-speaking intellectuals and drew 52. 3 per cent of the vote, to Lewis ' 22 per cent, or 1, 330 votes.

By about 1120 Gruffydd had grown too old to lead his forces in battle and Owain and his brothers Cadwallon and later Cadwaladr led the forces of Gwynedd against the Normans and against other Welsh princes with great success.

Hereford was again targeted by the Welsh during their conflict with the Anglo-Saxon King Edward the Confessor in AD 1056 when, supported by Viking allies, Gruffydd ap Llywelyn, King of Gwynedd and Powys, marched on the town and put it to the torch before returning home in triumph.

Gerald returned, and his cause was now supported by the Princes of Wales, most notably Llywelyn the Great, and Gruffydd ap Rhys II, while King John, frequently in conflict with the Welsh, warmly espoused the cause of the Archbishop of Canterbury.

As Penman explains: '“ After I ’ d finished Here Be Dragons, I knew I wanted to continue the story .... At first I ’ d planned to write one book in which Simon de Montfort would share top billing with Llewelyn Fawr ’ s grandson, Llewelyn ap Gruffydd, who later wed Simon ’ s daughter.

Talks with the Welsh began after the English lords Roger Mortimer and William de Briouze expanded into Welsh territory in 1195, causing a concern that the Welsh lord Rhys ap Gruffydd would strike back across the border.

Arthur seems to have been developed a close friendship with Gruffydd, and when Gruffydd himself died in 1521 prematurely his tomb was placed in Worcester Cathedral where Arthur himself rests.

In February 1263 royals armies gathered at Hereford and Ludlow to deal with incursions across the Welsh border by Llywelyn ap Gruffydd.

The King of Gwynedd, seeking to give up the exiled prince to Henry, ordered that the fugitive prince be dragged from the church by force, but his soldiers were beaten back by the local clergy ; Gruffydd ap Rhys escaped under cover of night and fled south to join up with his supporters in Ystrad Tywi.

* 1283 – Dafydd ap Gruffydd, prince of Gwynedd in Wales, becomes the first nobleman executed by being hanged, drawn and quartered.

Rhys was the second son of Gruffydd ap Rhys, ruler of part of Deheubarth, and Gwenllian ferch Gruffydd, daughter of Gruffudd ap Cynan, king of Gwynedd.

After driving Walter de Clifford out of Cantref Bychan, Gruffydd set off to Gwynedd to enlist the help of his father-in-law, Gruffudd ap Cynan.

In 1143, when Rhys was eleven, Anarawd was murdered by the bodyguard of Cadwaladr ap Gruffydd, brother of Owain Gwynedd, king of Gwynedd.

Owain Gwynedd and Gruffydd ap Rhys successfully captured considerable territories, including Carmarthen Castle.

* The cantrefs of Rhos and Rhufoniog are annexed by Gruffydd ap Cynan, King of Gwynedd.

* Gruffydd ap Cynan, King of Gwynedd

He led a series of successful campaigns ( 1062 – 63 ) against Gruffydd ap Llywelyn of Gwynedd, the ruler of Wales.

* August 5 – Gruffydd ap Llywelyn, King of Gwynedd

In 1246, his nephew Llywelyn the Last ( or Llywelyn ap Gruffydd ) succeeded to the throne of Gwynedd, and used the style as early as 1258.

In the 13th century, Llywelyn ap Gruffydd, ruler of Gwynedd, refused to pay homage to Edward I, King of England citing political hostilities.

Since the death of Owain Gwynedd in 1170, Rhys ap Gruffydd had made the southern kingdom of Deheubarth the strongest of the Welsh kingdoms, and had established himself as the leader of Pura Wallia.

Their sons included Llywelyn ap Gruffydd, who for a period occupied a position in Wales comparable to that of his grandfather, and Dafydd ap Gruffydd who ruled Gwynedd briefly after his brother's death.

Owain Gwynedd ap Gruffydd (; 1100 – 28 November 1170 ) was King of Gwynedd from 1137 until his death in 1170, and the first to be known as Prince of Wales.

He was known as Owain Gwynedd to distinguish him from another contemporary Owain ap Gruffydd, ruler of part of Powys who was known as Owain Cyfeiliog.