No house was ever built that could hold him and no ship could carry him, so when he crosses to Ireland he walks, with the fleet alongside. Irish swineherds report to their king that a forest has appeared on the sea with a mountain beside it, and a ridge on the mountain with a lake on either side of it. Branwen has to explain to the court that the mountain is her brother wading, the ridge is his nose, and the lakes are his eyes.
The Second Branch of the Mabinogi is the darkest of the four and Brân is at the centre of it: a king whose scale is the reason he can bridge two islands and the reason he cannot fit inside any of the structures that would contain an ordinary ruler.
The marriage, the horses, and the cauldron
He gives his sister Branwen to Matholwch, king of Ireland, to bind the two countries. His half-brother Efnysien, who was not consulted, responds by mutilating the Irish horses in their stalls — cutting lips, ears, tails and eyelids — which turns a wedding into an insult that cannot be undone by apology.
Brân pays compensation: new horses, a rod of silver as tall as Matholwch, a plate of gold the size of his face, and finally the cauldron of rebirth, in which a slain man placed overnight comes out alive the next day, able to fight but unable to speak. The cauldron's own back-story is that it came out of a lake in Ireland in the first place, carried by a giant couple Brân had sheltered — so the great gift is Irish property returning home, and it is the object that will kill everyone.
In Ireland the peace fails anyway. Branwen is put out of the royal chamber, set to work in the kitchen and struck daily by the butcher; she rears a starling, teaches it speech, and sends it across the sea with a letter. Brân comes.
Efnysien, and the worst scene in Welsh literature
The negotiations nearly succeed. A house is built large enough to hold Brân, which has never been done; the Irish hide two hundred armed men in flour-sacks hanging from the pillars; Efnysien walks the hall, asks what is in each bag, is told "flour", and crushes each man's skull through the sacking with his fingers.
Then a genuine settlement is reached, with the kingship of Ireland going to Gwern, Branwen's son and Brân's nephew. Efnysien calls the boy over, and throws him head first into the fire.
The battle that follows is unwinnable because the Irish dead keep being fed into the cauldron. Efnysien, finally understanding what he has done, hides among the corpses, is thrown in with them, and stretches until the cauldron bursts into four pieces and his own heart breaks. He is the most disturbing character in medieval Welsh writing: motiveless in his malice, and the only person who ends it.
Eighty years of good conversation with a severed head
Seven men survive on the Welsh side. Brân is wounded in the foot with a poisoned spear and tells them to cut off his head, take it to the White Hill in London and bury it facing France, and that on the way it will be as good company as it ever was in life.
It is. They spend seven years feasting at Harlech while the three birds of Rhiannon sing across the sea, and the head talks. Then eighty years on the island of Gwales — Grassholm, off Pembrokeshire — in a hall with three doors, one of which must not be opened, during which they age not at all, remember no sorrow, and are unaware of time passing. This period is called the Assembly of the Wondrous Head.
Eventually one of them opens the forbidden door, which faces Cornwall, and every loss they have ever suffered arrives at once. So they take the head to London and bury it.
The episode is one of the finest treatments of grief in medieval European literature, and it works by literal mechanism: as long as the door is shut, the death has not happened.
The head under the White Hill — and the ravens that are not connected to it
The Welsh Triads name the burial as one of the Three Fortunate Concealments of the Island of Britain: while the head lay hidden facing the Continent, no plague came across the sea. They also name its removal as one of the Three Unfortunate Disclosures, because Arthur dug it up, refusing to hold the island by any strength but his own.
The White Hill is generally taken to be the site of the Tower of London. From that identification, plus the fact that brân is the ordinary Welsh word for a crow or raven, comes the extremely popular claim that the Tower's ravens are Brân's, and that the kingdom will fall if they leave.
The claim does not survive checking. The prophecy about the ravens and the kingdom is not medieval; the earliest solid documentary evidence for ravens being kept at the Tower is late nineteenth-century, and research into the archives has failed to find the Charles II decree the story usually cites. The Welsh material and the Tower birds are two separate traditions joined together in the twentieth century by an attractive pun. The medieval text says nothing about ravens at the burial, and Brân's own bird associations are thin.
Bendigeidfran, and the Grail theory
His full name in the text is Bendigeidfran, "Brân the Blessed", and the epithet may well be a Christian overlay on an older figure — the Second Branch also has him carry a wounded-foot injury and preside over a vessel of restoration, which is why an older generation of scholars, Roger Sherman Loomis above all, argued that he lies behind the Grail king Bron and the Fisher King. The reasoning is suggestive: a maimed ruler, a wonder-working vessel, a wasteland, a Welsh name that looks like Bron.
It is also a chain of resemblances rather than a documented line of descent, and current opinion is much more cautious. It is worth knowing as a theory with a history rather than as an established fact.
His brother Manawydan survives him and carries the family into the Third Branch; the Welsh side of the Celtic family tree is built around their father Llŷr. The name Bran remains in use in Wales and Ireland, and has had a boost from fantasy fiction that has nothing to do with the Second Branch — name histories covers the modern usage.
Is Brân a god or a giant?
The text never calls him either. He is a king of Britain of superhuman size whose head goes on talking for decades, and the Triads treat him as a historical ruler of the island. Modern writers who label him a god are extrapolating from his scale and his cauldron; the honest description is that he behaves like a euhemerised deity without any text saying so — the same problem the Irish material has, arrived at from the other direction.
What is the cauldron of rebirth doing in the story?
Undermining the idea that violence can be reversed. Everything else in the branch is about compensation — a horse for a horse, silver for insult, a kingdom for a nephew — and the cauldron is compensation taken to its logical end, a machine that undoes killing. What it actually produces is mute soldiers who fight on and a war nobody can stop, and it has to be destroyed from the inside by the person who caused everything. It is an argument against the honour economy that the whole tale runs on.
How does the Second Branch end for Wales and Ireland?
Catastrophically for both, which is unusual. Ireland is left with five pregnant women hiding in a cave, from whom the whole island is repopulated and its five provinces named. Branwen lands at the Alaw in Anglesey, looks back at the two islands, says that two good islands have been laid waste because of her, and her heart breaks. A burial mound at Llanddeusant on Anglesey has been pointed out as hers since the nineteenth century, when a cist with an urn was found there.