A lion in host
In late 1253, after Dafydd had sworn homage to the king, Henry III ordered Owain Goch and Llywelyn to give their brother a reasonable share of their land. This was to be done according to Welsh custom, and without delay.
The brothers fell to arguing. In January 1254 Henry ordered four nobles to go to North Wales to mediate between Dafydd and Llywelyn, and listen to any complaints that Owain put forward. These lords were two Englishmen, Alan de Zouche and John Lestrange, and two Welsh, Gruffydd ap Madog of Powys Fadog and Gruffudd ap Gwenwynwyn. The parties were supposed to meet at Chester, five weeks before Easter, to settle any differences. A report of the outcome would then be sent to the king and council in London.
This all sounds very orderly, and no doubt Henry wanted it that way. However, the brothers had already taken matters into their own hands.
Owain and Dafydd had decided to join forces and destroy Llywelyn. Both sides raised armies and met in battle at Bryn Derwin, on the borders of Arfon and Eifionydd, in the middle of June 1255. Accounts of the battle are terse, but it seems Llywelyn seized the high ground and set up his army in a defensive position.
The allies attacked uphill, perhaps unwisely, and after an hour of fierce fighting Llywelyn's troops prevailed. Owain and Dafydd's men were scattered, and the brothers taken prisoner. Bleddyn Fardd, Llywelyn's court bard, composed one of his magnificent praise poems to celebrate the victory. Below is a partial translation of the Middle Welsh:
“Bryn Derwin!
He was the stay of a celebrated army!
There were no regrets the day he withstood,
The shameless attack of his own stock,
He who saw Llywelyn, the jubilation of warriors,
On the borders of Arfon and Eifionydd,
Would see a lord over men in hosts,
Like a man dispelling dishonour,
It was not easy, a lion in host and fearsome in combat,
To vanquish him by Drws Daunfynydd.”
The 'lion in host' now had to decide the fate of his rebellious brothers. Previous Welsh rulers had disposed of inconvenient siblings via brutal methods: this usually took the form of blinding and castration, with the unfortunate victim (if he survived)) packed off to a monastery for a life of contemplation. This was based on the theory that a man was unfit to rule if he was less than physically whole.
Times had changed. Under the rule of Dafydd's grandfather, Llywelyn ab Iorwerth - otherwise called Llywelyn the Great – the mutilation of political rivals was phased out. Llywelyn and his successors preferred to imprison their enemies, or bind their loyalty via financial penalties and the taking of hostages.
Llywelyn ap Gruffudd chose to adopt his grandfather's policy. After Bryn Derwin, he reigned supreme in North Wales, and might have killed his brothers. Instead he placed Owain in comfortable confinement at the castle of Dolbadarn, where the prisoner would spend the next twenty-two years. Dafydd, remarkably, suffered no punishment. It may be that Llywelyn chiefly blamed his eldest brother for the revolt, and regarded Dafydd as immature and easily led.
At any rate, Dafydd was given a chance to redeem himself. In 1256, after consolidating his power in Gwynedd, Llywelyn turned his attention to the land east of the River Conwy. This was the Perfeddwlad (Middle Country) or the Four Cantreds, overrun by Henry III in his previous invasion of North Wales. The king had since granted it to his eldest son, Lord Edward, destined to play such an important role in Welsh history.