Branwen (“white raven”) a daughter of Llyr and Penarddun, and sister of Bran, and Manawydan, and half-sister of Nisien and Efnisien. Matholwch of Ireland sued for her hand, and gave horses to Bran. Efnisien mutilated the horses, nearly precipitating warfare, but Matholwch was appeased by the gift of a cauldron that could resurrect the dead. Branwen wed him, and went to Ireland, where she bore him a son, Gwern. But the Irish began to complain about their foreign queen, and she was banished to the kitchen, where she was a slave and boxed on the ears by the butcher daily. This lasted three years, during which Branwen trained a starling to speak and sent it to Wales, where it told Bran of her plight, and he sailed to rescue her.Matholwch was terrified at the sight of a forest approaching Ireland across the sea: no one could make it out, until he called for Branwen, who explained it as Bran’s navy, and Bran himself wading through the water. He sued for peace, they built a house big enough for Bran, and Matholwch agreed to settle the kingdom on Gwern.
Some Irish lords objected, and hid themselves in flour bags to attack the Welsh. But Efnisien, scenting Irish treachery, cast them into the fire, and then cast Gwern himself in (avoiding the geas against shedding kinsmen’s blood thereby). A war broke out, and the Irish replenished themselves through the cauldron. Efnisien, repenting, sacrificed himself by feigning death and being thrown into the cauldron, which he then broke, dying in the process. Only seven Welshmen survived, and Bran was fatally wounded. His head, which remained alive and talking, was returned to Wales and buried, and soon afterwards Branwen sailed to Aber Alaw and died. She is one of the three “matriarchs of Britain”, along with (probably) Rhiannon and Arianrhod.