The Irish crowns

The de Vere chapter and the Clare chapter reached the Conquest from the English side, up the female lines of my father's grandmother. This chapter reaches something older, and it is Irish. Two of the crowns at the summit of this tree are Irish crowns, and they arrive not by any marriage into England but by the two daughters of one man: Diarmait Mac Murchada, King of Leinster.

Diarmait is the most consequential and most cursed name in Irish history: deposed in 1166, he crossed to Henry II, brought Strongbow and the Normans into Ireland, and died at Ferns in 1171 with the country he had opened already changing under him. The printed book reached him one way, through his daughter Aoife, 'Eva of Leinster', whom he married to Strongbow at Waterford in 1170, and from whom the Clare and Marshal and de Vere descents all flow. What July 2026 added is that Aoife was not his only daughter in this family. His elder daughter Órlaith, by his first wife Sadb of the Uí Faeláin, married Donal Mór O'Brien, King of Thomond, in an alliance struck the same years as her half-sister's. So I descend from Diarmait twice over, by two daughters, into the Norman line on one side and the Irish royal line on the other: the two invasions of Ireland meeting in one blood, four centuries before a Damery reached Cork.

Órlaith's husband, Donal Mór O'Brien, was the last King of North Munster, the man who founded the cathedral on the Rock of Cashel in 1169 and made his own submission to Henry II on the banks of the Suir in 1172. Behind him the O'Brien pedigree runs, king by king and prince by prince: Donogh Cairbreach, the first of the house to carry the surname O'Brien and the title Prince of Thomond; Connor-na-Siuddine, whose carved effigy still lies at Corcomroe Abbey; down through the lords of the Wars of Thomond to Turlogh Donn and Conor, third Earl of Thomond, and so to Lady Honora O'Brien, who married the Baron Kerry about 1594 and carried the blood into the FitzMaurice ladder the Piers chapter already climbed. And at the head of the whole line stands the name it all carries.

Brian Boru. Brian Boroimhe, High King of Ireland, Chief of the Dál gCais, born about 941 at Kincora above the Shannon at Killaloe, who broke the Norse power at the Battle of Clontarf on Good Friday 1014 and fell in his tent at the very moment of victory. He is the eponym of the surname O'Brien, 'descendant of Brian', and he is now a documented direct ancestor of this family, not a national boast borrowed for effect. The descent from him to Lady Honora O'Brien is set out generation by generation in O'Hart's O'Brien pedigree and the Irish annals, and it is corroborated by something the medieval genealogists never had: the O'Brien Y-DNA study, which independently numbers the same descent, Brian Boru to Turlogh Donn, and carries the Dalcassian marker the male line still bears. It is as close to proof as a thousand-year Irish descent is ever going to come.

Above Brian Boru the wiring stops, and it stops honestly. His father Cennétig and the Dál gCais stem run back in the old pedigrees through Cas and Cormac Cas to Milesius and Noah, exactly the fashion in which every Irish house once traced itself to Adam; modern scholarship reads the deepest reaches as a tenth-century dynastic fiction, and here they are kept note-only, the same frontier this tree keeps for Cerdic and Woden above Alfred and the Carolingians past Charlemagne.

The Leinster crown has a deep climb of its own, and it comes in by Órlaith's mother. Sadb of the Uí Faeláin was a daughter of Cerball mac Faeláin, and the Uí Faeláin were one of the three ruling septs of the Uí Dúnlainge, the dynasty that held the kingship of Leinster in rotation for three centuries from their seat at Naas on the Liffey plain. Through Sadb the line climbs, king after king of Leinster, to Dunlaing mac Enda Niada, the eponymous founder of the whole dynasty, said to have been a contemporary of Saint Patrick in the late fifth century: the deepest rung the documented tree now touches on any side, English or Irish. Above Dunlaing the pedigrees pass into the legendary High King Cathair Mór and the ancestor-figures of the Laigin, and there, as everywhere, the wiring stops and the note-only frontier begins.

My father wanted a line to the Conquest and found it, at last, up the English side of the tree. He would not, I think, have dared to want this: that the same research, in the same weeks, would carry the Irish side of the house back past the Normans he resented, to the High King who fought them, and past him again to a king of Leinster in Saint Patrick's century. It is the truest thing the whole ascent discovered. The family never had to choose between its Irish blood and its grand English descents. It turns out to have owned both, one blood, long before the name it carries was ever heard in Bandon. The whole of it, crown by crown and king by king, is drawn in The Royal Houses.