1 November 527 AD: After Muircheartach [Muirchertach Mac Erca] … had been twenty four years in the sovereignty of Ireland, he was burned in the house of Cleiteach, over the Boyne, on the night of Samhain [the first of November] after being drowned in wine.
Annals of the Four Masters
These were the battles of: Cenn Losnada, Inne Mór, Segais, Cenn Eich, Áth Sige, Éblenn, Mag Ailbe, Aidne, Almuin, and the 2nd battles of Cenn Eich and Áth Sige.
King Muirchertach came to a bizarre end, being drowned in a vat of wine. This strange event took place somewhere about the location of those ancient Neolithic passage tombs, Knowth, Dowth and Newgrange. It would appear that this was a planned royal assassination in which the King’s body was to be left unblemished but his soul sent to eternity. Possibly his death was due to an internal family rivalry due to him taking a much younger mistress - a woman by the name of Sín!
Sín is the woman that killed thee,
O, Mac Earca, as I perceive;
Numerous will her names be here—
She will set one astray.
It must be said though that the various Annals differ as to the year of his death it would appear to have been circa 530 AD and on the night of Samhain [31 October/1 November]