John, hopeful of avoiding trouble in England and Wales while he is away fighting to recover his French lands, forms an alliance in 1205 by marrying off his illegitimate daughter, Joan, to the Welsh prince Llywelyn the Great, who had previously been negotiating with Pope Innocent III for leave to marry his uncle Rhodri's widow, daughter of Ragnald, King of Mann and the Isles.

This proposal had been dropped, however.

Llywelyn allies himself with the baronial faction in England in 1265 in exchange for being granted authority over the local Welsh magnates across all the territories in the region, including Glamorgan.

De Clare, believing his lands and power are under threat, has now allied himself with Henry III against the rebel barons and Llywelyn.

…the mountains above the Welsh royal home in Abergwyngregyn.

Dafydd and his younger son Owain ap Dafydd are captured on June 22 at Nanhysglain, a secret hiding place in a bog by Bera Mountain to the south of Abergwyngregyn.

Dafydd, seriously wounded in the struggle, is brought to King Edward's camp at Rhuddlan that same night (Cotton Vesp. B xi, f30).

Dafydd is taken from here to Chester and then on to Shrewsbury.

Dafydd's wife Elizabeth de Ferrers, their daughter Gwladys, infant niece Gwenllian ferch Llywelyn, and Dafydd's six illegitimate daughters were also taken prisoner at the same time.

Whether they were with Dafydd and Owain at Bera is not recorded, but it is likely.