The distressful island of Ireland was at this moment enjoying the anarchy which had reigned therein since the dawn of history. Its state had grown even more unhappy than before since the Danish invasions of the 10th century, which had not welded the native kingdoms into unity by pressure from without as had been the case in England but had simply complicated affairs, by setting up two or three alien principalities on the coastline. As in England, the vikings had destroyed much of the old civilization; but they had neither succeeded in occupying the whole country nor had they been absorbed by the natives.
The state of the island was much like that of England in the days of the Heptarchy: occasionally a High King succeeded in forcing his rivals into a precarious submission; more usually there was not even a pretence of a central authority in the island, and the annals of objectless tribal wars formed its sole history. King Henry's eyes had been fixed on the faction-ridden land since the first years of his reign. As early as 1155 he had asked and obtained the approval of Pope Adrian IV, the only Englishman who ever sat upon the papal throne, for a scheme for the conquest of Ireland. The Holy See had always regarded with distaste the existence in the West of a nation who repudiated the Roman obedience, and lived in schismatical independence, under local ecclesiastical customs which dated back to the 5th century, and had never been brought into line with those of the rest of Christendom. Hence it was natural to sanction an invasion which might bring the Irish within the fold. But Henry made no endeavour for many years to utilize the papal grant of Ireland, which seems to have been made under the preposterous Donation of Constantine, the forged document which gave the bishop of Rome authority over all islands. It was conveniently forgotten that Ireland had never been in the Roman empire, and so had not even been Constantine's to give away.
Not till 1168, thirteen years after the agreement with Pope Adrian, did the interference of the English king in Ireland actually begin. Even then he did not take the conquest in hand himself, but merely sanctioned a private adventure of some of his subjects. Dermot MacMorrough, king of Leinster, an unquiet Irish prince who for good reasons had been expelled by his neighbours, came to Henry's court in Normandy, proffering his allegiance in return for restoration to his lost dominions. The quarrel with Becket, and the French war, were both distracting the English king at the moment. He could not spare attention for the matter, but gave Dermot leave to enlist auxiliaries among the turbulent barons of the South Welsh Marches.
The Irish exile enlisted first the services of Maurice Fitzgerald and Robert Fitzstephen, two half-brothers, both noted fighting men, and afterwards those of Richard de Clare, Earl of Pembroke, an ambitious and impecunious magnate of broken fortunes. The two barons were promised lands, the earl a greater bribe the hand of Dermot's only daughter Eva and the inheritance of the kingdom of Leinster. Fitzgerald and Fitzstephen crossed to Ireland in 1169 with a mere handful of followers. But they achieved victories of an almost incredible completeness over Dermot's enemies. The undisciplined hordes of the king of Ossory and the Danes of Wexford could not stand before the Anglo-Norman tactics the charge of the knights and the arrowflight of the archers, skilfully combined by the adventurous invaders. Dermot was triumphant, and sent for more auxiliaries, Ispiring to evict Roderic O'Connor of Connaught from the precarious throne of High King of Ireland.
In 1170 the Earl of Pembroke came over with a larger force, celebrated his marriage with Dermot's daughter, and commenced a series of conquests. lie took Waterford and Dublin from the Danes, and scattered Lhe hosts of the native princes. Early in the next spring Dermot died, and Earl Richard, in virtue of his marriage, claimed the kingship of Leinster. He held his own, despite the assaults of a great army gathered by Roderic the High King, and of a viking Fleet which came to help the conquered jarls of Waterford and Dublin. At this moment King Henry thought it necessary to nterfere; if he let more time slip away, Earl Richard would ecome a powerful king and forget his English allegiance. Accordingly, with a large army at his back, he landed at c in 1171 and marched on Dublin. Richard did him homage for Leinster, engaging to hold it as a palatine earldom, and not to claim the name or rights of a king. The other adventurers followed his example, as did, after an interval, most of the native Irish princes. Only Roderic of Connaught held aloof in his western solitudes, asserting his independence. The clergy, almost without a murmur, submitted themselves to the Roman Church.
Such was the first conquest of Ireland, a conquest too facile to be secure. Four years later it appeared to be completed by the submission of the king of Connaught, who did homage like the rest of the island chiefs. But their oaths were as easily broken as made, and the real subjection of the island was not to be completed for 400 years. What happened was that the Anglo-Norman invaders pushed gradually west, occupying the best of the land and holding it down by castles, but leaving the profitless bogs and mountains to the local princes. The king's writ only ran in and about Dublin and a few other harbour fortresses. Inland, the intruding barons and the Irish chiefs fought perpetually, with varying fortunes. The conquest hardly touched central and western Ulster, and left half Connaught unsubdued: even in the immediate vicinity of Dublin the tribes of the Wicklow Hills were never properly tamed. The English conquest was incomplete; it failed to introduce either unity or strong governance. After a century and a half it began to recede rather than to advance. Many of the districts which had been overrun in the time of the Angevin kings were lost; many of the Anglo-Norman families intermarried with and became absorbed by the Irish; they grew as careless of their-allegiaiice to the crown as any of the native chiefs. The Lordship of Ireland was never a reality till the times of the Tudors. But as long as Henry II lived this could not have been foreseen. The first generation of the conquerors pushed their advance with such vigour that it seemed likely that they would complete the adventure.
Text extracted from the entry for ENGLISH HISTORY in the 1911 Encyclopedia Britannica, the text of which lies within the public domain.