Dallán mac Móre, fl. c. 900, was an Irish poet, and chief bard to King Cerball mac Muirecáin of Leinster (reigned 885-909. The poem The Song of Cerball's Sword is attributed to Dallán.
Cath Bealach Mughna
Sub anno 903, the Annals of the Four Masters preserve part of a lament on those killed at the battle of Bealach Mugna:
References
Dallán mac Móre Wikipedia(Text) CC BY-SA