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":-- "When her kings with standard of green unfurled Led the Red Branch Knights to danger." 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.