So Cormac, disciplined in adversity, came to the throne in the year A.D. 227, according to the Four Masters.[29] During the earlier years of his reign he was engaged in continual wars with the provincial kings, who had yet to learn that Cormac was their master in fact as well as of right. We are told that he fought no less than fifty battles against these turbulent kings to vindicate his own position as High King of Erin. The accurate Tighernach furnishes us with brief notices of those various battles against the refractory sub-kings. In one year he fought three battles against the Ultonians. In another he fought four times against the Momonians. The Leinster King, Dunlaing, taking advantage of Cormac’s absence from Tara, attacked the royal rath itself, and wantonly slaughtered thirty noble maidens with their attendants—thirty for each—who lived in a separate building on the north-western slope of Tara. Cormac promptly avenged this awful massacre by invading Leinster, and putting to death twelve sub-kings of that province; and besides he increased and enforced the payment of the ancient Borumean or cow-tribute imposed by his predecessors on the same province. The Ultonians, however, were his most inveterate foes; and twice, it seems, they succeeded in “deposing” him, that is, in driving him for some months from Tara. At length, however, the king gained a complete victory over his northern rivals, with the aid of Tadhg, a grandson of Ollioll Olum, and his Munster auxiliaries. Cormac rewarded the Munster hero by giving him, as he had promised, as much of the territory of Meath as Tadhg could drive round in his chariot from the close of the battle till sunset. The veteran hero, spent with loss of blood and battle-toil, still contrived to drive his chariot round a district extending from Duleek to the Liffey, which was afterwards called Cianachta—the land of Cian’s descendants. Tadhg’s father was Cian, son of Ollioll Olum, hence the name.

Cormac, now undisputed master of his kingdom, took measures to preserve the public peace and secure the prosperity of his dominions. He was the first, and we may say also, the last king of Erin, who maintained a standing army to check the arrogance of his turbulent sub-kings. This Fenian militia was, it is said, modelled after the Roman legions, which Cormac might have seen, or heard of at that time in Britain. They were quartered on the people in winter; but in summer they lived on the produce of the chase, and gave all their leisure to martial exercises. By this means they became most accomplished in all feats of arms, so that the fame of these Fenian heroes has come down to our own time in the living traditions of the people. The celebrated Finn Mac Cumhail was their general—a poet too, it was said, he was, and a scholar, as well as a renowned warrior. Ossian, the hero-poet, was his son; and the brave and gentle Oscar, who fell in the fatal field of Gabhra, was his grandson.

We are also told that Cormac kept a fleet on the sea for three years, and doubtless swept away the pirate ships of Britain and the islands, that used to make descents from time to time on the eastern coasts of Ireland.

But it is with the literary history of King Cormac’s reign we are most concerned, and to this we invite the special attention of the reader. His first work was to re-establish the ancient Feis of Tara.

Tara even then had been the residence of the High Kings of Erin from immemorial ages. Slainge, the first king of the Firbolgs, was its reputed founder; and all the kings of that colony, as well as of the Tuatha De Danaan and Milesian race, had usually dwelt on the same royal hill. Ollamh Fodhla, one of the most renowned kings in the bardic history, “reigned forty years and died in his own house at Tara.” It is said that this king was the first who convened the great Feis of Tara to legislate in solemn assembly for all the tribes of Erin. O’Flaherty adds that the same ancient monarch founded a “Mur Ollamhan,” or college of learned doctors at Tara; but Petrie could find no authority for this statement except the term “Mur Ollamhan,” which might, however, simply mean the mur, or fortified house of Ollamh Fodhla himself.

During the shadowy period that follows down to the Christian era, we hear little of Tara even in bardic history. An undoubtedly historical king, Tuathal Teachtmar, about the year 85 of the Christian era, took a portion of each of the four provinces to make a mensal demesne for the High King of Tara. He convened the states of the kingdom, too, on the royal hill in solemn assembly, and induced the assembled kings and chiefs to swear by all the elements that they would always yield obedience to the princes of his own race.

The Feis of Tara, then, was in existence before the time of Cormac; but it was seldom convened, and had almost fallen into disuse. Cormac it was, who made arrangements for the regular meetings of that great parliament of the nation, and provided adequate accommodation for the assembled notables. Here we are on firm historic ground and can enter into more minute details with security.

The object of this Feis of Tara was mainly three-fold.[30] First, to enact and promulgate what was afterwards called the cain-law, which was obligatory in all the territories and tribes of the kingdom, as distinguished from the urradhus, or local law. Secondly, to test and sanction the Annals of Erin. For this purpose each of the local Seanachies or historians brought in a record of the notable events that took place in his own territory. These were publicly read for the assembly, and when duly authenticated were entered on the great record of the King of Tara, called afterwards the “Saltair of Tara.” Thirdly, to register in the same great national record the genealogies of the ruling families, to assess the taxes, and settle all cases of disputed succession among the tribes of the kingdom. Too often this was done by the strong hand; but it was Cormac’s idea to fix the succession, as far as possible, according to definite principles amongst the ruling families. The absence of a strong central government to enforce this most wise provision was one main cause of the subsequent distracted state of the kingdom.

This great national assembly, convened for these purposes, met once every three years. The session continued for a week, beginning the third day before, and ending the third day after November day. When so many turbulent chieftains, oftentimes at feud amongst themselves, met together, it was necessary to keep the peace of Tara by very stringent regulations, enforced under the most rigorous penalties. It is to Cormac’s prudent forethought we owe these regulations, which were afterwards inviolably observed as the law of Tara. Every provincial king and every sub-king had his own fixed place allotted to him near the High King by the marshals of Tara; and every chief was bound to take his seat under the place where his shield was hung upon the wall. Brawling was strictly forbidden, and to wound another was a capital crime.

In order to provide suitable accommodation for this great assembly, Cormac erected the Teach Miodhchuarta, which was capable of accommodating 1,000 persons, and was at once a parliament house, banquet hall, and hotel. We have two accounts of this great building, as well as of the other monuments at Tara, written about nine hundred years ago—one in poetry, the other in prose. The statements made by these ancient writers have been verified in every essential point by the measurements of the officers of the Ordnance Survey, who were enabled from these documents to fix the position and identity of all those ancient monuments at Tara.