[3] This origin story, the Expulsion of the Deisi, is covered by Power which is believed to be a fictitious tale created by prominent families of the Desies to justify their elevation to Gaelic nobility from a former tributary status.
[4] According to historian C. Thomas Cairney, the O'Phelans were the chiefly family of the Déisi who were a tribe of the Erainn who were the second wave of Celts to settle in Ireland between about 500 and 100 BC.
[5] Keating speaks of Cellachán Caisil King of Munster plundering the town of Waterford, causing its leader Sitiric to take flight.
Donnoavan was killed in revenge for this deed a week later, Domhnall son of Faelan is later recorded as having died but the cause is unknown.
Brian Bóruma then gave battle and defeated them at Fan mic Connrach; they were then chased to Waterford where Domhnall and most of the foreigners (Ostmen) were slain and the town was plundered and burned.
The Cogadh Gaedhel Re Gallaibh places Mothla with Magnus King of the Ui Liathain at the head of Brian's second battalion, which is described as very great and strong and formed from the chosen hosts of all Munster.
Both the Annals and the Cogadh report Mothla's death at this battle along with Brian, his sons, the King of Leinster, many of the Norse Gael leaders and numerous others.
[17] Melaghlin O’Phelan, Prince of the Desies, was amongst the defenders of Waterford during Strongbow's (Richard de Clare) taking of the town in the summer of 1170.
It appears that this son of O'Faelain was part of a coalition including Rory Mac Donslevy, the English, and chieftains of Connaught.