Connected apparently with the tribal sentiment were the strange customs of fosterage and gossipred. Fosterage consisted in putting out the child to be reared by a tribesman who became its foster-father. Gossipred, a Christian addition, was a spiritual kinship formed at the font. Both relations had extraordinary force.

There were, of course, tribal wars. There were leagues or dominations of powerful tribes which left their traces in the division of the island into four or five provinces, once petty kingships. There was a supreme kingship, the seat of which, sacred in Irish tradition and legend, was the Hill of Tara; but it was probably only when common danger compelled a union of forces that this kingship became a real power. The features of the country, combined with the character of the tribal organization based on kinship, not on citizenship, would prolong the tribal divisions and prevent union. Nor had nature anywhere fixed a central seat of command. Only when opposed to an invader and struggling against him for the land did Celtic Ireland form for the time a united people; even then it could hardly be called a nation.

The Roman conqueror looked, but came not. It might have been better for Ireland if he had come. Yet, when he retired, he would probably have left the Romanized provincial, here as in Britain, too unwarlike to hold his own against the next invader.

A conqueror of a different kind came. He came in the person, not of a Roman general, but, if the tradition is true, of a slave. By the preaching of St. Patrick, according to the common belief, Ireland was added to the Kingdom of Christ. The conversion was rapid and probably superficial, the chief of the tribe carrying the tribe over with him, as Ethelbert of Kent and other English kinglets carried over their people, rather to a new religious allegiance than to a new faith.

Within the Roman Empire the centres of the Church had been the cities. Cities were the seats of its bishoprics. The models of its organization were urban. But in Ireland there were no cities. The episcopate was irregular and weak, denoting rank rather than authority or jurisdiction. The life of the Church was monastic and missionary. The weird Round Towers, believed to have been places of refuge for its ministers and their sacred vessels, as well as bell-towers, speak of a life surrounded by barbarism and rapine as well as threatened by the heathen and devastating Northmen. Partly perhaps owing to its comparative isolation and detachment at home, the Irish clergy was fired with a marvellous and almost preternatural zeal for the propagation of the Gospel abroad. It crossed the sea to Iona, the sacred isle, still to religious memory sacred, from which the light of the Gospel shone to the wild islesmen and to the rovers of the Northern Sea. Irish missionaries preached to heathen Germany, colliding there, it seems, with a more regular episcopate. They played a part in the conversion of Britain not less important than that of the missionaries of Rome, before whose authority, however, the Irish Church in the person of Aidan was at last compelled to retire, the decisive struggle taking place on the mode of celebrating Easter.

In Ireland itself there arose in connection with the Church a precocious and romantic passion for learning which founded primitive universities. Its memory lingers in the melancholy ruins of Clonmacnoise. This was the delusive brightness of a brief day, to be followed by the darkness of a long night.

The Church of Ireland seems in its origin to have been national and neither child nor vassal of Rome. Its theology must have been independent if Scotus Erigena was its son. But Rome gradually cast her spell, in time she extended her authority, over it. Its heads looked to her as the central support of the interests of their order and as their protectress against the rude encroachments of the native chiefs. Norman Archbishops of Canterbury served as transmitters of the influence. Still, the Irish Church was not in Roman eyes perfectly regular. Tithes were not paid, nor was the rule of consanguinity observed, or the rite of baptism administered in strict accordance with the ordinances of Rome.

Christianity did not kill the brood of a lively superstition, the fairy, the banshee, the spectre, charms, amulets, prophecies, wild legends, which in the times of gloom that followed strengthened their hold upon Irish imagination.

Hostile invasion came first in the form of the Northmen, whose piracy and rapine extended to Ireland as well as to Gaul and Britain. Piracy and rapine we call them now, but to the Northmen they seemed no more criminal than to us seems hunting or fishing. The chief objects of the invader’s attack were the monasteries, at once treasuries of Church wealth and hateful to the people of Odin. Ruthlessly the Northman slew and burned. His fleet made him ubiquitous and baffled defence, union for which there was not at first among the tribes. Common danger at last enforced it. A national leader arose in the person of Brian Boru, who was for Ireland the military, though not the political, saviour that Alfred was for England. At the great battle of Clontarf, the host over which the Danish Raven flew was totally overthrown, and Ireland was redeemed from its ravages. The Dane, however, did not wholly depart. Exchanging the rover for the trader, he founded a set of little maritime commonwealths at Dublin, Wexford, Waterford, and Limerick, germs on a small scale and in a rude way of municipal as well as commercial life.

But a conqueror, more fell and more tenacious than the Dane, was at hand. In 1169 a little fleet of Welsh vessels ran into the Bay of Bannow. From it landed a band of mail-clad soldiery, men trained to war, with a corps of archers. They were Normans from Wales under the leadership of the Anglo-Norman rover Fitzstephen, and were the precursors of a larger body which presently followed, under Richard Strigul, Earl of Pembroke, from the strength of his arm surnamed Strongbow. Dermot, an Irish chief, expelled for his tyranny, had brought these invaders on his country as the instruments of his revenge. Henry II. had, by giving letters of marque, sanctioned the enterprise, the fruits of which he intended to reap. Early in his reign the king had obtained from Pope Adrian IV., an Englishman by birth, a bull authorizing him to take possession of Ireland, which with other islands the bull declared of right to be an appanage of the Holy See. Here, as in the case of William’s invasion of England, the Papacy used Norman conquest as the instrument of its own aggrandizement. The authenticity of the bull is disputed by Irish patriotism, but in vain. No one questions the share of the Papacy in the Norman conquest of England.