I was reading about The Battle of Clontarf in 1014 where Irish High King Brian Boru defeated a coalition of Norse-Irish (but was slain, with his son and grandson in an ambush on their tent). Do we know much about these battles and how they were fought? Specifically, do we know anything about the Irish tactics which let them defeat the Vikings?
In particular, it seems they changed tactics somehow, as inferred from Binchy:
in pre-Norse times, all wars, inter-tribal and inter-provincial alike, followed a curiously ritual pattern. They were hedged around with taboos; one did not continue to fight after one’s king had been slain; one did not annex the enemy’s territory or confiscate any of their land; one did not dethrone the ‘sacred’ tribal dynasty; one refrained from attacking a number of ‘neutral zones’ on enemy soil—the monastic settlements, the property of the learned castes (áes dána), and so on. Now, however, the Irish found themselves faced with an alien foe who respected none of the traditional conventions ~…
As a follow up, if I may, how did Ireland not descend into political anarchy with 3 generations of Royalty killed in one ambush? It seems remarkable that Clontarf was considered the turning point which marks the reduction of the Norsemen to a minor power given the damage to the Irish political infrastructure. (Though perhaps a clue can be found in the Binchy quote above, "one did not dethrone the 'sacred' tribal dynasty" so perhaps they went to 4 generations (derbfhine) instead of just 3 (gelfhine) but that is pure speculation on my part.)
The quote you give from Binchy dates to the early 1960s. Since that time Binchy’s views of pre-Viking Ireland have been challenged by many scholars most notably by Charles Doherty and Donnchadh Ó Corráin.
Ó Corráin makes the case against Binchy that
“These opinions derive from too narrow and too selective an interpretation of the Irish law texts, deeply coloured by literary texts of uncertain date that are open to a different interpretation… The ‘old order’ is very much the product of Binchy’s singular reading of the law tracts The annals and genealogies tell a different story and reveal a pre-Viking Ireland ruled by aristocrats and kings, some claiming to be kings of Ireland, who had long been engaged in precisely the activities he would refer to the Viking impact—and engaged in them for a long time.
Quote taken from Viking Ireland—Afterthoughts: Donnchadh Ó Corráin. I have a hard copy of the paper but you should be able to find it online at the celt.ucc.ie site.
Ó Corráin poses the question of “why were Viking conquests in Ireland limited and peripheral while large parts of England and Scotland were relatively easily taken?” Pre-Viking Ireland was a society dominated by an aristocratic elite who were highly cognizant of a native society that had cultural and linguistic union. The Irish scribes saw the Irish as a people similar to the Goths, the Franks, or the peoples of classical antiquity. The other reason for the limited Viking inland incursions is that the Irish took the struggle with the Vikings very seriously and reacted with decisiveness. The Vikings had successfully settled in Irish coastal areas but first inland incursions were met by violent resistance and counter attacks. Many Irish kings gave their lives in fighting the Vikings. The Battle of Tara in 980 was a major defeat for the Viking ambitions in Ireland and just as significant as the Battle of Clontarf – some argue more significant because it weakened the Viking presence and held them to the Irish coastal areas. Many scholars believe that without the success at Tara the Battle of Clontarf in 1014 would have been a much more difficult endeavour for the Irish.
Ó Corráin also makes the point – in support of Irish resistance - that Viking invaders who failed in Munster in the early tenth century succeeded readily in York.
As to the other question you have about the aftermath of Clontarf. The details of the battles are recorded in the Irish annals. The Annals of Inisfallen are a good source with some interesting details about where the Viking ships landed on the Dublin coast at Clontarf, the local rivers they attempted to come up, and even about banners carried into battle at Clontarf by Boru’s side.
Yes, Brian was slain in his tent in the aftermath of the battle and his son Murchadh was killed in the battle. Primogenitor was not at all the usual practice in Ireland so it was not obvious that Brian's son would have succeeded him. Nevertheless political chaos ensued later as other regional kings fought for the right to the High Kindship. This went on for some time but it’s important to note that it would have been localised and did not engulf the entire population of Ireland. The fight for the High Kingship would eventually lead to the first Anglo-Norman incursions as an Irish King, Diarmait Mac Murchada, [Dermot MacMurrough] the loser in a battle for the High Kingship, went overseas in search of support. Henry II of England was happy to oblige with what essentially became a full scale invasion of Ireland beginning in the 1160s.