The Deasy Family

Deasy family crest

(Crest No. 215. Plate 32.)

THE Deasy family is descended from Milesius, King of Spain, through the line of his son Heremon. The founder of the family was Fiacha Suidhe, brother of Con of the Hundred Battles, King of Ireland, A. D. 148. The ancient name was Deasad and signifies “Prettiness.” The possessions of the clan were located in ancient Deisi, in Munster.

Deise, or Deisies, was a territory comprising the greater part of the present County of Waterford, with a part of Tipperary, and derived its name from the tribe of the Deisigh (whence Deasy), also called Desii. Their original territory was in Meath and was called Deise Teamrach, or Deise of Tara, because situated near Tara; and the name of this ancient territory is still retained in the two baronies of Deece, in the County of Meath.

In the reign of Cormac McArt, the one hundred and fifteenth monarch of Ireland, Aongus, or Æneas, Prince of Deise, in Meath, grandson of Fiacha Suidhe, resenting the exclusion of his own branch of the family from the monarchy, waged a rebellion against Cormac McArt; but Cormac having quelled the rebellion in seven successive battles drove Aongus and his successors into Munster, where they obtained settlements from Olliol Ollum, then King of Munster, who granted them the lands extending from the River Suir southward to the sea and from Lismore to Cean Criadain, now Creadan Head, thus comprising almost the whole of the territory afterward called Waterford, and they gave to that country the name of Deise, or Nandesi, which was called Deisi, in Munster, to distinguish it from Deise, in Meath. The Desians being numerous and powerful in Munster, Aongus, or Æneas, King of Munster in the fifth century, conferred on them additional lands and annexed to their territory Magh Feimin, which extended north of the River Suir as far as Corca Eathrach, comprising the country called Machaire Caisil, or the Plain of Cashel, and districts about Clonmel, forming the present barony of Middlethird, with part of Offa, in Tipperary. The territory comprised in this grant of King Aongus was distinguished by the name of Deise Tuaisceart, or North Desie, and the old territory in Waterford was called Deise Deisceart, or South Desie. The name of Deisie is still retained in the two baronies of Decies, in the County of Waterford.

The Deasys were chiefs also in the barony of Ibane and Barryroe. The name was honorably noted in the Irish Brigade in the service of France.