Ireland has a singular history. Unlike England, it was never part of the Roman Empire. There was trade with the Roman Empire most importantly with Roman England, and Ireland was culturally influenced by the Roman Empire. For instance, a Roman script replaced the primitive and clumsy Ogham script. In the period of the final decline of Rome, the Irish joined the other barbarians in raiding Roman and immediately post-Roman England for loot, including slaves. Among those slaves was, famously, the future Saint Patrick. Legend has it that Irish raiders penetrated east as far as what is now Switzerland. A civilised Dublin nationalist lawyer in the early 1840s, Thomas Davis, would sit down and write triumphalist verse about "The Fate of King Daithi" on such a raid, as some Mongols today glory in Genghis Khan, and some Georgians in Stalin.
Ireland became Christian by contact with Roman-British Christianity. It developed a religion that differed from the institutions and culture of the Church in post-Roman-Empire Europe. A lay intelligentsia existed in Christian Ireland, a remnant of the old druidic priesthood, while in the rest of Christian Europe the priests gained a monopoly on literacy. After Greece and Rome, Ireland had the oldest vernacular literature in Europe. Irish Christianity was centred on monasteries. In the Dark Ages, when babarians ruled Europe in the ruins of the Roman Empire, Ireland became the chief source of learning in Western Europe. Europeans in Charlemagne's time who wanted to learn Greek, for instance, went to Ireland. Irish missionaries converted much of Europe to Christianity, the northern half of England included. This learning and culture, however, subsisted in monasteries, islands in society, not among the people. Frederick Engels wrote: "Whilst the people made no, or only extremely slow, social advances, there soon developed amongst the clergy a literary learning which was extraordinary for the time and which, in accordance with the custom then, manifested itself mostly in zeal for converting heathens and founding monasteries... Before this development of culture could have an effect on the people, it was interrupted by the raids of the Norsemen" [ "Ancient Ireland", in Marx and Engels on the Irish Question].
There was a deep-rooted antagonism between Irish Christianity and its ways, and the Roman Catholicism of the rest of Europe, and there were differences that were enormously important to the people of that time, such as on dating Easter and on the tonsure of monks. (Early Irish Christianity adopted a Japanese-style shaving of the front of the head, above the forehead; Roman, the shaving of the top of the poll). From late Viking times and then after the Norman-English invasion of 1169-71, there would be two distinct Catholic churches in Ireland, an Anglo-Norman one in the English "Pale", and the church of the Gaelic-Irish.
In Irish society, by contrast to Christian Europe, central social institutions, importantly marriage, were not religious sacraments. In that respect the Irish church has been compared to the Coptic. Secular Irish marriage implied and included the right to easy divorce. There was no "whom God has joined together, let no man put asunder". European Catholic and English critics insisted that there was something very like polygyny and polyandry, at least among the upper classes. Thus the well-known historical figure of Gormlaith, wife seriatim of Malachy, Brian Boru's rival, and (Malachy still living) of Brian, and also mother of the Danish King of Dublin. This remained so until Renaissance times. "Irish ways and Irish laws", and Irish Christianity, were for centuries a source of scandal throughout Christian Europe. Ireland was not, to put it that way, *Roman* Catholic. Clerics agitated against Ireland, as being not Christian in the European sense.
There were many small states in Ireland, but no unified Irish state. There never was an all-Irish state, until the island was unified by English conquest and integrated administration early in the 17th century. The island shared a common language (divided into dialects) and culture, perhaps in a way something like the separate ancient Greek city states had shared culture and religion and mythology. Inside most of the small states there were, much of the time, civil wars over the kingship, local equivalents of the English War of the Roses, multiplied many times over hundreds of years. There was an office of High King, Ard Ri, king of the littler kings, and occasionally it was held by a man who made it a powerful force for a generation or so; but that depended on the character and ability and local power base of the Ard Ri, and so was unstable. Such was Brian Boru, king of Munster and Ard Ri, who united much of Ireland for a while against some of the Danish settlements. But in his final battle, at Clontarf in 1014, where Brian and his allies won, but Brian lost his life, there were Irish and Vikings on both sides. The Vikings had been more or less absorbed into the porous Irish political system, except in Dublin. The last strong, "imperialistic", High King was Thurlough O'Connor of Connaught, in the first half of the 12th century.
Whether Gaelic Ireland would have evolved some variety of feudalism, given time, is an unanswerable question. Independent Irish evolution was ended forever by the Anglo-Norman invasions of 1169-1171. Henry II made himself feudal king of the Irish kings, and in 1175, by the Treaty of Windsor, made himself Liege Lord of the last crowned Ard Ri, Rory O'Connor, Thurlough's unworthy son. From that point on, Ireland and England were entwined.
The area of English control, "the Pale", an area radiating out from the old Danish or Viking city of Dublin, fluctuated over centuries, but in tendency it shrank, to not much beyond Dublin. The historian Lecky compared the Pale to a lance stuck into the political body of Ireland, preventing Irish unification, in a way comparable perhaps to the effect of the Papal States on the possibility of Italian unity, over centuries. There was a "Gaelic revival" from about 1350 to 1500, meaning the reconquest of territory once held by the Anglo-Normans, and it shrank the Pale towards Dublin. It used to be celebrated in the official ethnic-sectarian version of Irish history, but, all in all, this was social and political regression. It involved the exaction of tribute from towns and other centres of Anglo-Norman colonisation, and helped retard their development. In the Middle Ages, when there were large-scale movements of peasants throughout Europe, a sizeable colonisation by English peasants occurred in Ireland.
So two systems of society existed in Ireland, in the English and in the Irish territories. Two distinct Catholic churches existed, one in the Pale (from late Viking times, and then under the Anglo-Normans) which conformed to the practices and rules of the English and European Catholic churches, and one in the Irish or mainly Irish areas which did not. Strong animosities existed between those two branches of one church. Agitation against the Irish church and its ways by the bishops of the Pale and Catholic prelates throughout Europe was an element in the Pope's decision of 1155 to give Ireland to England's Henry II. Irish church and social practices continued to be a scandal to the rest of Christendom until the Renaissance and up to the end of the 16th century. A sort of tribalism survived in some of Ireland, but these were not tribes practising "Gaelic communism" and common ownership of the land, as mythology has it, but tribes and local small kingdoms with aristocracies, peasant subordination, and even slavery.
Partly gaelicised Anglo-Norman nobles, adopting some of the old Gaelic customs, became great as overlords under the English monarchy, most famously the Fitzgeralds in Leinster. These hybrids adapted to themselves the Irish traditions of lords' rights - such as "coyne and livery", the billeting of their armed retinues on "their" tenants. Those continued even after Henry VII had suppressed the equivalent noble private armies in England. They imposed crushing burdens on those whom they ruled. Their typical exactions drove most of the English settler-peasants out of the country.
As has been said, there was a strong sense of separateness between the Gaelic Irish and the "men of the Pale", and between their churches too; and a strong antagonism between the Irish areas and the Anglo-Norman towns. As early as the start of the 14th century, a complaint to the Pope was sent by Irish lords in Ulster telling of their exclusion and being supplanted by the Anglo-Normans. Records exist of mobilisation of the townsfolk of Drogheda, the tradesmen and the journeymen, to fight off the invasion of Edward Bruce, brother of Robert Bruce, king of Scotland, who had much Gaelic support and laid waste to much of the country.
All these things shaped the Ireland that faced new assaults in the late 16th century from English adventurers who eyed the country rapaciously and were intent, as some of them wrote, on transforming it into their "empire", as South America was Spain's. Ireland's "gold" was very fertile land, herds of cattle, and great forests. A man like Sir Walter Raleigh involved himself in colonising both America and Ireland. Ireland was hybridised and undeveloped compared to England. The towns were bourgeoisifying islands in a Gaelic Irish sea. There was as yet no sense of Irishness or nationalism. Those in Ulster who would fight the English and ally with England's enemy Spain in the 1590s, Hugh O'Neill, Earl of Tyrone, for the chief example, had helped England crush the Munster rebellion after 1579. The Tudor reconquest and unification of Ireland was finished by 1603. It is a sobering fact that serfdom was formally declared at an end in Ireland by the English Dublin rulers as late as 1604-5, using it as a weapon to undermine Hugh O'Neill. Spanish troops had landed in Munster in 1601 to help the Irish. From that point on, military considerations were important for England: the will not to let Ireland become a base for its enemies (after Spain, the French, for nearly 200 years).
The theme of Catholicism vs Protestantism made its first appearance during the Munster wars of the late 16th century. the first note of a tune that would drown out all others for centuries to come. The leaders proclaimed themselves Catholics fighting for the true religion against the heretical English. Fervent missionary priests began to educate the Irish in Catholicism. Over 50 years the English tried to "plant" "loyal" state-organised English settler-colonists in various parts of Ireland. None of the plantations was successful, not even the Plantation of Ulster, in replacing native Irish with "loyal" English people. The present-day heartlands of Irish Protestantism were not "planted", but became Protestant by way of free migration, mainly from lowland Scotland. There had always been close ties between Scotland and north-east Ireland, and even at one time a kingdom spanning both sides of the narrow sea, Dalriada. A number of times - from the Catholic Queen Mary's plantation in present-day Offaly and Laois, to the Williamite confiscation of the 1690s - the land in different areas of Ireland was confiscated and given to great English landlords. The native Irish, now decidedly *Roman* Catholic, in part for reasons other than intrinsic religious feeling and belief, were dispossessed. The tenants in most of Ireland were without rights. Anti-Catholic "Penal Laws" were imposed: a system of exclusion very like that of South African apartheid, except that Catholics could change their religion. In effect it outlawed the majority of the Irish people. As the 19th century nationalist Thomas Davis wrote in his verse, The Penal Days:
"They bribed the flock, they bribed the son,
To sell the priest and rob the sire;
Their dogs were taught alike to run
Upon the scent of wolf and friar.
Among the poor,
Or on the moor,
Were hid the pious and the true".
The Protestant settler tenants in Ulster could negotiate terms with their landlords akin to terms in England. The Catholic tenants, by contrast, were a conquered people, and they had no right even to benefit from improvements they had made, or capital they might have invested in the land. If they were evicted or left, it was the property of the landlord.
Ireland was enmeshed to an England that experienced a profound bourgeois-democratic revolution in the 1640s and a supplementary revolution, securing the achievements of the 1640s, in the "Glorious Revolution" of 1688. In 1641, during the English revolution of the 1640s, Catholic Ireland rebelled, and became for that decade part of the Catholic camp in a religion-divided Europe. The Thirty Years' War, which laid Germany to waste for generations, would not end until 1648. The most important Irish military commander, the Irish-Spanish Owen Roe O'Neill, had fought for Catholic Spain against the Protestants in the Lowlands. The most powerful political leader among the Catholic Irish was the Papal Nuncio, Cardinal Giovanni Battista Rinuccini. The Catholic Irish were allied with Anglo-Irish aristocrats in Ireland, the so-named "Old English", who supported Charles I in the English civil war. The invasion of Ireland in 1649, led by the military victor in the English civil war, Oliver Cromwell, was seen in England as completing the war against the English Royalists. The English Parliament had raised money to fight the King on speculative sales of Irish land that then had to be conquered - and was. The Cromwellian massacres on which most discussion of Cromwell's conquest focus, those at Drogheda and Wexford for instance, were to a serious extent massacres of English Royalists taking refuge there. Such treatment of cities that refused to surrender was commonplace in Europe then. Cromwell's butchery and atrocities against the Gaels are neatly summed up in the saying among Cromwell's soldiers, to justify killing Irish children: "nits will make lice".
The Irish rising of 1641 started in Ulster against the Protestant settlers, some of whom were killed. The story can be seen in many US "Western" movies: the Indians rise and massacre some of the settlers, driving the rest to seek shelter in the nearby fort. The massacres of the Ulster Protestants in 1641, greatly exaggerated, were used to justify the massacre and dispossession of Irish Catholics in 1649 and after. The land was confiscated and given to new overlords. They remained in possession after the British monarchy was restored in 1660, the king not daring to dispossess them. There is dispute about whether Cromwell's decrees banishing Irish people to the west - "to hell or to Connaught" (meaning present-day Connaught and County Clare) - referred to landowners or to the whole Gaelic population. In any case, only Catholic landlords went. The labouring people remained. under new masters who could not do without them.
Protestant Ulster, and the Protestants scattered across the island, achieved their bourgeois-democratic revolution with Cromwell's reconquest of Ireland. They took an active part in securing it in 1688-9, in events still commemorated in Orange marches. At that point Ireland was the only base of support for the English king, James II, in his attempt to restore absolute monarchy. The 1688 revolution was bloodless in England; the fighting was done in Ireland, between James's Irish army, with French armies sent by France's absolute monarchy, and the armies of Parliament, including Dutch soldiers and exiled French Protestants driven out of France after 1685 by Catholic persecution.
The defeated Irish were plunged, by the victory of the English and Protestant-Irish bourgeois-democratic revolution, for a hundred years into a condition of helotry under penal legislation enacted by the Irish Protestant parliament. The Catholic Irish ruling class fled to Europe, as did the Irish soldiers of James's army.