Sixth century.
Both published and unpublished copies of the Tallagh Martyrology assign the
1st day of January as a festival to Ossene, of Cluana Mor. This is the name
of a parish and townland in the ancient territory of
Cianachta Arda, It is known as Clonmore, in the present barony of Ferrard,
county of Louth. Ossein, son to Ceallach, of Cluainmor-Fer-n Arda, according
to the Martyrologies of Marianus O'Gorman and of Donegal, was venerated on
this day. This saint flourished at an early period, since St. Columkille
founded or repaired Cluain-mor-fernarda, in the territory of Bregia,and
placed St. Ossin, or Osseneus over it
(
O'Hanlon).