re: "The Buik of the Cronicles of Scotland" (search Google books). "How Eugenius, the King of the Scottis passit in Gallowa with ane armie aganis the Saxonis and Pechtis.
And king of Pechtis with mekle bost and schoir, By the se coist with all thair power lay, Segeand ane castell callit wes Dunskey." ...................... "Historical and Traditional Tales in Prose and Verse, Connected with the South of Scotland" Edited, printed and published by John Nicholson, Kirkcudbright, Scotland, 1843. p.36 "About the year 615, in the reign of Eugene V, King of Scotland, Egrid, King of Bernicia, laid siege to the castle of Dunskene (Dunsky) in Galloway."
Would this be a castle further north than Adair's castle near Portpatrick, Wigtownshire ?There was a moat in the front of Adair's Dunskey Castle, but it looks to me that it would have been easy to invade.