By the 1100’s AD, the Norman conquest of both England and Ireland was well under way.

Irish society was still a conglomeration of small kingdoms with several regional dynasties vying with each other for total kingship over the whole land.

As infighting became worse, the King of Leinster, Diarmuid Mac Morrough, was forcibly exiled by the new High King of Ireland,Conchobair. Diarmuid fled to the safety of England, where he managed to persuade the King of England, Henry II, to supply Norman soldiers to help him regain his rightful place in Ireland.

The full force landed in Wexford in 1169 and quickly regained Leinster.

Diarmuid,in trying to protect his dynasty, named his son-in-law, the Earl of Pembroke as his immediate heir.
However once Henry II learned of this, he feared a rival for his throne might easily arise in Ireland and in 1171, he himself landed at Waterford with a large fleet, overcoming all and sundry who stood in his way.

At the same time, the Irish churches had joined together in a loose-fit type of association which seemed to be an affront to the Papacy. This enraged the Pope, Adrian IV, an Englishman, who gave Henry his full blessing to use whatever means necessary to solve the "Irish problem."

Henry immediately proclaimed his son John as “Lord of Ireland”, and when the younger son suddenly and unexpectedly found himself on the English throne, he immediately placed the “Lordship of Ireland” under the full control of the English crown.

During the period 1185 to 1210, John visited Ireland several times and consolidated the Norman grip on the whole country by politically and physically ensuring that the Irish kings swore their "loyalty" to him.

In time however, a number of battles between the native Irish and Norman offspring,showed the weakening of the long-standing ruler-ship,and in 1315, Edward the Bruce of Scotland invaded Ireland, seeking support for his war against the English.

Although the Bruce was defeated at the battle of Faughart, the English/Scottish wars created a chaotic situation in Ireland by which many of the local lords took back their family lands and re-established their own ruler-ship over specific areas of the country.

The Norman rule over Ireland continued to be weakened and in 1348 when the dreaded “Black Death” plague spread throughout the whole of Europe and Britain, decimating the populace by the thousands, it wreaked havoc on the towns and villages where the vast majority of Normans lived.

The native Irish had tenaciously clung to their rural,isolate lifestyle,and it was this that saved them from the devastation of a disease that could have depopulated the whole country.

As the disease dispersed, the old Irish customs and ways returned to the fore.

The only truly English controlled area was around Dublin. In the rest of the country, the lords re-adopted the Irish language and sided with the native population, moving away from English influences and turning more to Roman Catholicism as the “accepted” faith of the time.