What was the genealogical connection between Peadar Ua Laoghaire, the famous priest and author, and Art Ua Laoghaire, killed in 1773 for refusing to sell his horse to an English officer? It is frequently stated that they are related distantly but the exact relationship is seldom spelled out.
What information is available in Peadar Ua Laoghaire’s Mo Sgéal Féin can be seen in a PDF I have drawn up. I will probably eventually redraft this, but you can see that PUL–my abbreviation for Peadar Ua Laoghaire–is descended from Diarmuid and Conchobhar Ua Laoghaire, who abandoned Carrignacurra in the 17th century. He is descended in the male line from Diarmuid and through his mother from Conchobhar. But the name of their father is not given.
However a passage in the book Máire Bhuí Ní Laoire: a poet of her people by Brian Brennan shows exactly the same history: two brothers Diarmuid and Conchobhar forced to leave Carrignacurra–and their father was Conchobhar Meirgeach Ua Laoghaire, who died in 1699. There was a Conchobhar Meirgeach Ua Laoghaire who is stated to have been the second cousin of the Ua Laoghaire chieftain Dómhnall Mac Airt, and combining other genealogical information–and assuming it is all accurate–the relationship becomes clearer, if not totally clear.
Conchobhar Meirgeach Ua Laoghaire must be a descendant of Tadhg Meirgeach Ua Laoghaire, who was the son of Diarmuid Óg Ua Laoghaire, who flourished in Carrignacurra in 1565. A report in 1584 showed Tadhg had a son called Conchobhar who was the second cousin of Dómhnall Mac Airt – but it can’t be the same Conchobhar, as it is unlikely someone alive in 1584 died in 1699. There was probably one or two additional generations between our Conchobhar Meirgeach and Tadhg Meirgeach himself. Alternatively, the 1699 date for the death of Conchobhar could be wrong.
Anyhow, Diarmuid Óg Ua Laoghaire was son of Diarmuid Mór Ua Laoghaire, also called Diarmuid ny Countie. He is the common ancestor of Peadar Ua Laoghaire and Art Ua Laoghaire. Diarmuid Mór’s older son was Conchobhar Ua Laoghaire of Manneen, who died in 1575. His sons Art, Amhlaoibh Ruadh and Donnchadh were successively Ua Laoghaire chieftains 1572-1597, 1597-1601 and 1601-1638, with the chieftainship then passing to Art’s son Dómhnaill. A fourth son of Conchobhar Ua Laoghaire of Manneen was Conchobhar Óg, father of the Art Ua Laoghaire of Tirgea who was outlawed in 1641, who was in turn father of Art Óg Ua Laoghaire, who leased Tirgea in 1677. His son was Lisagh Ua Laoghaire of the Gearagh, who died in 1683. His son was Céadach Ua Laoghaire, “Old Cady of Tirgeah” who died in 1747, and his son and grandson were Conchobhar (“Cornelius”) Ua Laoghaire of Rathleigh and Art Ua Laoghaire, who was born in 1746 and murdered in 1773.
The two men are probably eighth cousins, although the exact nature of the Meirgeach link remains unclear to me.