She screams while she is still in the womb. The men of Ulster, feasting in her father's house, are so alarmed that Cathbad the druid is asked what it means, and he puts his hand on the woman's belly and delivers a prophecy: a girl of extraordinary beauty, over whom kings will contend, and because of whom there will be slaughter in Ulster.
The warriors want her killed at birth. Conchobar refuses — and his reason is not mercy. He will have her reared apart, in a place no one may visit, and marry her himself when she is grown.
Longes mac nUislenn, the Exile of the Sons of Uisliu, is one of the oldest tales in the Ulster Cycle, with a version surviving in the Book of Leinster and language pointing to composition several centuries earlier. It is short, cold, and structurally perfect.
The raven, the snow and the calf
Deirdriu grows up in isolation with a foster-mother and a woman named Leborcham, a satirist who cannot be barred from anywhere. In winter, her foster-father is skinning a calf outside in the snow, and a raven comes down to drink the blood.
She says she could love a man who had those three colours: hair like the raven, cheek like the blood, body like the snow. Leborcham tells her that such a man is not far away — Noísiu, son of Uisliu, at Conchobar's court.
The colour triad is one of the oldest and most widespread images in European literature and it appears here in a version with no fairy-tale softening: what is on the ground is a butchered animal. She is not dreaming of a prince. She is looking at meat in the snow and identifying what she wants.
The elopement, and the sureties
She waylays Noísiu and forces the issue by seizing his ears and shaming him — a formal act, in a culture where a warrior's honour is public property — so that he cannot refuse without disgrace. He and his brothers Ardán and Ainnle take her and flee, first around Ireland, then to Scotland, where they take service with a king who eventually wants her too, and they move again.
Ulster misses them. Fergus mac Róich and others press Conchobar to allow their return, and he agrees, sending Fergus as guarantor with two other sureties. On landing, Fergus is caught by an obligation he cannot refuse — an invitation to an ale-feast, which he is bound never to decline — and has to send the party on to Emain Macha with his son instead. Noísiu and his brothers are killed on arrival, in a killing arranged around the technicality that Fergus himself was not there.
Fergus burns Emain Macha and goes into exile in Connacht, which is why he is fighting on Medb's side when the Cattle Raid of Cooley begins. This tale is not a romantic interlude in the cycle; it is the reason Ulster's best warriors are in the enemy army.
What she says at the end
Deirdriu spends a year with Conchobar without smiling. He asks her what she hates most, and she says: you, and Eogan mac Durthacht, the man who killed Noísiu. So he tells her she will spend the next year with Eogan.
She is put in a chariot between the two men, and Conchobar jeers that she is like a ewe between two rams. She throws herself out and dashes her head against a rock.
The Old Irish version ends there, with her laments preserved as verse: praise of the sons of Uisliu, of the Scottish glens, of a life that was not the one she was assigned. There is no consolation and no divine intervention. It is the bleakest ending in the cycle and one of the very few in which a woman's judgement of the men around her is the last word.
The two yews said to have grown from her grave and Noísiu's, meeting above them so that they could not be separated, belong to a later retelling. The motif of intertwining trees over lovers' graves recurs across medieval European literature, and this is one of its early appearances in Irish — but it is an addition, and the earliest text does not soften the ending that way.
Synge, the revival, and the name
She became, in the Irish Literary Revival, one of the central subjects. Yeats wrote a Deirdre, AE wrote one, Lady Gregory retold the tale in Cuchulain of Muirthemne, and John Millington Synge left Deirdre of the Sorrows unfinished at his death in 1909; it was completed for the stage by Yeats and Molly Allgood, and is now the version most often performed.
That surge of attention did two things at once. It brought the tale to an English-reading public, and it attached to her the epithet "of the Sorrows", which is not in the Old Irish. The medieval Deirdriu is angry rather than sorrowful, and considerably more dangerous.
Deirdre has been a widely used given name in Ireland, Britain and North America since the early twentieth century, a direct result of the revival rather than of any continuous tradition — one of the clearest cases of a literary movement putting a name into circulation. Name histories follows that separately.
Is she a sovereignty figure in disguise?
Some readers have argued it: a woman whose union determines who rules, a king who must have her to hold his position, a kingdom that collapses when the arrangement fails. The tale can be read that way, and its interest in Conchobar's legitimacy supports it. But the text itself is remarkably secular and psychological, and nothing supernatural attaches to her beyond the prenatal prophecy. Treating her as a goddess in narrative disguise explains the plot at the cost of the character.
Why does Fergus's obligation to accept a drink outweigh a guarantee of safety?
Because both are the same kind of thing, and that is the tragedy. A geis and a suretyship are both absolute personal bonds, and Irish law had no general rule for what happens when two of them collide. Conchobar's plan works precisely because he knows Fergus cannot refuse the ale-feast, so a man's honour is used as the mechanism for breaking his word. The tale is a demonstration that a system built entirely on personal obligation can be dismantled by anyone who understands it well enough.
How does the later version differ?
Oidheadh Chloinne hUisneach, the early modern retelling that most popular versions descend from, is longer, more romantic and much more sympathetic to everyone. It gives the lovers speeches, expands the Scottish exile into an idyll, has Deirdre die of grief over the body rather than by suicide against a rock, and adds the yews. It is a fine piece of storytelling. It is not the old tale, and almost every children's version and stage adaptation is working from it.