Gruffydd ap Llywelyn died in 1244 leaving 3 sons - Owain, Llywelyn and Dafydd.
On the death of their uncle Dafydd, Owain and Llywelyn were persuaded to divide the land of Gwynedd between them. These two continued the war with Henry III throughout 1246, but were outflanked by an English army which pushed from the South of Wales sweeping all before it until it reached Degannway.
Following a truce made at Chester, Owain and Llywelyn met Henry at Woodstock on 30th April 1247.
Henry claimed and received homage from all Welsh princes, including them. He gave back to them the land west of the Conwy, but they were forced to surrender all the territory between Conwy and the Dee. This constituted the 4 Cantrefs of Rhos, Rhufaniog, Dyffryn Clwyd and Tegeingl. (A Cantref was a division of land, containing about 100 villages.) These now passed to the English crown.
Henry further fragmented Gwynedd in 1252 by donating land to Dafydd, the youngest of the three brothers.
It was these lands of the 4 Cantrefs that Henry donated to his 15 year old son Edward in 1254. Although they came to Edward in the calm that follows battle, they came like a pot about to come to the boil.
In 1251 Alan la Zouche, justice of Chester, was very unpopular in the 4 Cantrefs. Henry III agreed to hear complaints against his man through a commission of 2 Welsh and 2 Englishmen.
But Edward's Steward, Geoffrey de Langley, brooked no such interference. A former officer of Queen Eleanor, he had been chosen by the King and Council. He was a greedy and unscrupulous man, who did much to sour Anglo-Welsh relations.
On 17th July 1256 Edward, aged 17, visited Chester before proceeding up the coast first to Dyserth and then Degannwy. He left Chester on 3rd August.
Rebellion broke out, when Edward's subjects realised that the visit had left Langley in charge. Llywelyn came to the aid of his countrymen. Crossing the Conwy in force on 1st November 1256 he retook all the land surrendered at Woodstock. Gwynedd was back to its original boundaries.
In December Llywelyn invaded Meirionydd and ejected Henry's vassal. As the year closed he seized Gwerthrynian from Roger Mortimer, the Marcher Lord.
As the year turned Llywelyn moved south into Powys and then the Gower peninsula.
Young Edward had not the men to deal with this emergency, nor the money to hire more. The Earls of Gloucester and Hereford were left to do the best they could. The King only gave his firstborn 500 marks to aid him, whilst his uncle Richard of Cornwall donated 4,000.
In June 1257 Edward launched a counter-attack. A large English, Welsh and Gascon force landed at Caermarthen on Tuesday 29th June. They were led by Stephen Bauzan. On Thursday they marched down the Roman road which runs parallel to the River Tywi towards the Castle of Dinefwr near Llandeillo. Their guide was Rhys Fychan, who had lost lands to Llywelyn. They covered the fifteen miles to Dinefwr reaching it on Friday 1st June. Purporting to take the castle's surrender Rhys switched sides, leaving the English army at the mercy of a far larger Welsh force in the hills. Bauzan tried to retreat to Caermarthen on Saturday 2nd June but was attacked repeatedly. It seems that he and most of his men perished in the withdrawal.
Finally the pathetic Henry woke up to the peril of his state.
Henry mustered his army at Chester on 1st August. Edward accompanied the expedition, which set out along the north cost reaching Degannwy in the late August. As usual Henry had not planned adequately. He had been in too much haste to retaliate. When his men began to run out of food and fresh supplies did not arrive from Edward's holdings in Ireland, the English were compelled to make an ignominious retreat, harrassed all the way by the Welsh.
The young Lord Edward learned some bitter lessons from these first contacts with the Welsh. But learn them he did, as the future would unfold.