Gods and Fighting Men, by Lady Gregory [1904], at sacred-texts.com
Now as to Manannan the Proud, son of Lir, after he had made places for the rest of the Tuatha de Danaan to live in, he went away out of Ireland himself. And some said he was dead, and that he got his death by Uillenn Faebarderg, of the Red Edge, in battle. And it is what they said, that the battle was fought at Magh Cuilenn, and that Manannan was buried standing on his feet, and no sooner was he buried than a great lake burst up under his feet in the place that was a red bog till that time. And the lake got the name of Loch Orbson, from one of the names of Manannan. And it was said that red Badb was glad and many women were sony at that battle.
But he had many places of living, and he was often heard of in Ireland after. It was he sent a messenger to Etain, mother of Conaire the High King, the time she was hidden in the cowherd's house. And it was he brought up Deirdre's children in Emhain of the Apple Trees, and it was said of that place, "a house of peace is the hill of the Sidhe of Emhain." And it was he taught Diannuid of the Fianna the use of weapons, and it was he taught Cuchulain the use of the Gae Bulg, and some say it was he was Deirdre's father, and that he brought Conchubar, king of Ulster, to the place she was hidden, and he running with the appearance of a hare before the hounds of the men of Ulster to bring them there.
And it is what they say, that the time Conchubar had brought the sons of Usnach to Emain Macha, and could not come at them to kill them because of their bravery, it was to Manannan he went for help. And Manannan said he would give him no help, for he had told him at the time he brought Deidre away that she would be the cause of the breaking up of his kingdom, and he took her away in spite of him. But Conchubar asked him to put blindness for a while on the sons of Usnach, or the whole army would be destroyed with their blows. So after a while he consented to that. And when the sons of Usnach came out against the army of Ulster, the blindness came on them, and it was at one another they struck, not seeing who was near them, and it was by one another's hands they fell. But more say Manannan had no hand in it, and that it was Cathbad, the Druid, put a sea about them and brought them to their death by his enchantments.
And some say Culain, the Smith, that gave his name to Cuchulain afterwards, was Manannan himself, for he had many shapes.
Anyway, before Culain came to Ulster, he was living in the Island of Falga, that was one of Manannan's places. And one time before Conchubar came into the kingdom, he went to ask advice of a Druid, and the Druid bade him to go to the Island of Falga and to ask Culain, the smith he would find there, to make arms for him. So Conchubar did so, and the smith promised to make a sword and spear and shield for him.
And while he was working at them Conchubar went out one morning early to walk on the strand, and there he saw a sea-woman asleep on the shore. And he put bonds on her in her sleep, the way she would not make her escape. But when she awoke and saw what had happened, she asked him to set her free. "And I am Tiabhal," she said, "one of the queens of the sea. And bid Culain," she said, "that is making your shield for you, to put my likeness on it and my name about it. And whenever you will go into a battle with that shield the strength of your enemies will lessen, and your own strength and the strength of your people will increase."
So Conchubar let her go, and bade the smith do as she had told him. And when he went back to Ireland he got the victory wherever he brought that shield.
And he sent for Culain then, and offered him a place on the plains of Muirthemne. And whether he was or was not Manannan, it is likely he gave Cuchulain good teaching the time he stopped with him there after killing his great dog.
Manannan had good hounds one time, but they went hunting after a pig that was destroying the whole country, and making a desert of it. And they followed it till they came to a lake, and there it turned on them, and no hound of them escaped alive, but they were all drowned or maimed. And the pig made for an island then, that got the name of Muc-inis, the Pigs Island afterward; and the lake got the name of Loch Conn, the Lake of the Hounds.
And it was through Manannan the wave of Tuaig, one of the three great waves of Ireland, got its name, and this is the way that happened.
There was a young girl of the name of Tuag, a fosterling of Conaire the High King, was reared in Teamhair, and a great company of the daughters of the kings of Ireland were put about her to protect her, the way she would be kept for a king's asking. But Manannan sent Fer Ferdiad, of the Tuatha de Danaan, that was a pupil of his own and a Druid, in the shape of a woman of his own household, and he went where Tuag was, and sang a sleep-spell over her, and brought her away to Inver Glas. And there he laid her down while he went looking for a boat, that he might bring her away in her sleep to the Land of the Ever-Living Women. But a wave of the flood-tide came over the girl, and she was drowned, and Manannan killed Fer Ferdiad in his anger.
And one time Manannan's cows came up out of the sea at Baile Cronin, three of them, a red, and a white, and a black, and the people that were there saw them standing on the strand for a while, as if thinking, and then they all walked up together, side by side, from the strand. And at that time there were no roads in Ireland, and there was great wonder on the people when they saw a good wide road ready before the three cows to walk on. And when they got about a mile from the sea they parted; the white cow went to the north-west, towards Luimnech, and the red cow went to the south-west, and on round the coast of Ireland, and the black cow went to the north-east, towards Lis Mor, in the district of Portlairge, and a road opened before each of them, that is to be seen to this day.
And some say it was Manannan went to Finn and the Fianna in the form of the Gilla Decair, the Bad Servant, and brought them away to Land-under-Wave. Anyway, he used often to go hunting with them on Cnoc Aine, and sometimes he came to their help.