Nearly two miles west of Armagh are the remains of the ancient palace of Emain, or Emain Macha, often called Emania. They consist of a great circular rath or rampart of earth, with a deep trench outside it, and a high mound within, the whole structure covering a space of about thirteen acres. At one time the circular ring was complete, but of late years some portions of it have been levelled or removed. The houses in which the kings and heroes of old, with their numerous households, lived and feasted, stood mostly within the enclosure, and were all of wood, not a trace of which remains. This great fort is now called by the people of the place, the "Navan Fort," or "Navan Ring."

According to Irish legendary history, Emain was founded about three centuries before the beginning of the Christian era, by Macha of the Golden Hair, queen of Ulster; and for more than six hundred years it was the residence of the kings of that province. But about the year A.D. 331, it was destroyed by three princes from Tara, who invaded and conquered that part of Ulster; after which Emain was no longer inhabited.

Early in the first century of the Christian era flourished the Red Branch Knights, a band of heroes in the service of Concobar (or Conor) Mac Nessa, king of Ulster. There were several bodies of them, under separate commanders, who lived in different parts of the province. These leaders were the great heroes of the Red Branch, who are celebrated in ancient Irish romance, and who are mentioned by Moore in his song, "Let Erin remember":—

Every year during the summer months, various companies of the Knights came to Emain under their several commanders, to be drilled and trained in military science and feats of arms. They were lodged in a large separate building beside Emain, called Creeveroe or the Red Branch—from which the whole force took its name: and the townland in which this great house stood is still called Creeveroe. Each day the leaders were feasted by King Concobar Mac Nessa in his own banquetting hall at Emain.

The greatest of all the Red Branch heroes was Cu-Culainn—"the mightiest hero of the Scots," as he is called in one of the oldest of the Irish books—whose residence was Dundalgan, a mile west of the present town of Dundalk. This dun or fort consists of a high mound surrounded by an earthen rampart and trench, all of immense size, even in their ruined state; but it has lost its old name and is now called the Moat of Castletown, while the original name Dundalgan, slightly altered, has been transferred to Dundalk.

Another of these Red Branch Knights' residences stands beside Downpatrick: viz., the great fort anciently called (among other names) Dun-Keltair or Rath-Keltair, where lived the hero, Keltar of the Battles. It consists of a huge embankment of earth, nearly circular, with the usual deep trench outside it, covering a space of about ten acres.

Next to Cuculainn, the most renowned of those knights were Fergus Mac Roy, Leary the Victorious, Conall Carnagh, and the three Sons of Usna.

There were, at this same time, similar orders of knights in the other provinces. Those of Munster were commanded by Curoi Mac Dara, who lived in a great stone fortress high up on the side of Caherconree Mountain, near Tralee, the remains of which may be seen to this day. He was a mighty champion, and on one occasion vanquished Cuculainn in single combat. The Connaught knights were in the service of Maive, the warlike queen of that province, whose residence was the palace of Croghan, the ruins of which still remain near the village of Rathcroghan in the north of Roscommon.

In the Book of the Dun Cow, the Book of Leinster, and other old manuscripts (which will be found described farther on), there are great numbers of romantic stories about those Red Branch Knights, and about the Knights of Munster and Connaught, of which many have been translated and published.

The most celebrated of all these tales is what is called the Tain or "Cattle spoil" of Quelna or Cooley.[18] Queen Maive, having some cause of quarrel with an Ulster chief, set out with her army for the north on a plundering expedition, attended by all the great heroes of Connaught. During the march northwards, the queen, as the story tells us, had nine splendid chariots for herself and her attendant chiefs, her own in the centre, with two abreast in front, two behind, and two on each side, right and left; and—in the words of the old tale—"the reason for this order was, lest the clods from the hoofs of the horses, or the foam-flakes from their mouths, or the dust raised by that mighty host, should strike and tarnish the golden diadem on the head of the queen."

The invading army entered Quelna, which was then a part of Ulster and belonged to Cuculainn. It happened just then that the men of Ulster were under a spell of feebleness, all but Cuculainn, who had to defend single-handed the several fords and passes, in a series of combats against Maive's best champions, in all of which he was victorious. But, in spite of what he could do, Queen Maive carried off nearly all the best cattle of Quelna, and, at their head, a great brown bull which indeed was what she chiefly came for. At length the Ulstermen, having been freed from the spell, attacked and routed the Connaught army. The battles, single combats, and other incidents of this war are related in the Tain, which consists of one main story, with about thirty minor tales grouped round it. Another Red Branch story is the Fate of the Sons of Usna, which has been always a favourite with Irish story-tellers, and with the Irish people in general, and which is now given here, translated in full.