Today is the 850th anniversary of the landing of King Henry II in Ireland and can be seen as the beginning of his, and his successors, Lordship of Ireland which was to become in 1542 the Kingdom of Ireland. Its symbolic significance led to a painting of King Henry II receiving the homage of the Irish Kings and chiefs being included in the late eighteenth century scheme of decoration of the ceiling of St Patrick’s Hall in the State Apartments of Dublin Castle.
The background and course of the Norman invasion of Ireland is set out by Wikipedia at Anglo-Norman invasion of Ireland
There is an article on the Erenow website about the arrival of King Henry by the well-known historian of the Angevin rulers John Gillingham, who has also published works on medieval Anglo-Irish relations, which can be read at 1171: Henry II invades Ireland - The Great Turning Points of British History
The same site has a good summary of the King and his governance at King Henry II, Britain and Ireland, 1154–89 - The Struggle for Mastery: Britain 1066-1284
Wikipedia has a detailed discussion of the 1155 Papal Bull Laudabiliter which apparently gave authorisation for King Henry II to rule Ireland, and the debate about the authenticity of the text, at Laudabiliter
Recent decades have seen something of a revision of the interpretation of the history of Ireland before 1534 or 1541 ( never mind for later centuries ) and, an ever important theme in Irish historiography, in the use of politically charged terminology suc as “Irish”, “colonial”, “Home Rule” when applied to the medieval centuries and to the whole pre-1800 history of the island. For me reading the work of Steven G. Ellis Ireland in the Age of the Tudors1447-1603: English Expansion and the End of Gaelic Rule, in the Longman History of Ireland was an eye-opener to this process and to how one can view medieval Ireland. It is a book I highly recommend. I know Prof. Ellis’s ideas do not meet with universal acceptance in Ireland but I think he and his school do offer a much more constructive interpretation of Irish history as part of a wider picture of north west Europe at the time.
In this centenary year of partition and with the latest moves over the Northern Ireland Protocol it does seem appropriate to urge people across Ireland and Britain, and those far beyond, to look at the historical evidence and its interpretation of Irish history rather than, as seems so often to happen, recycling nineteenth and early twentieth century views, themselves shaped by political debates that are now themselves part of that complex historical process.