27 December 1171 AD: Petrus Ua Mórda [ang: Peter O’Moore) the Bishop of Clonfert/Clúain Fearta in what is now Co Galway, was drowned on this day in the River Shannon/Abhainn na Sionainne close by the seat of his Diocese.

He appears to have been a member of a family from Ui Maine, one of the oldest and largest kingdoms located in Connacht, Ireland. Ua Mórda was abbot of Grellach dá Iach, the first of three sites inhabited by the Cistercians and who finally settled at Boyle Abbey. In around 1150 AD, he became Bishop of Clonfert; styled as Bishop of Cluain-fearta-Brenainn or Bishop of Ui Maine.

Petrus (Ua Mordha), bishop of Ui-Maine of Connacht (otherwise, bishop of Cluain-ferta of [St.] Brenann), a devout monk and authoritative man, was drowned in the Sinand (namely, at Port-da-Chaineg), namely, on the 6th of the Kalends of January [Dec. 27].

Annals of Ulster