In 1555/6, Calvagh O’Donnell was engaged in bitter warfare with his father Manus O’Donnell over the Lordship of Donegal. It is often said that no dispute is as bitter as an internal family battle and the consequences of this particular personal squabble had long-lasting consequences. Backed by a team of “enforcers”, Calvagh sailed to Scotland to get assistance form Archibald, Fourth Earl of Argyle. It was known that he had a nice selection of modern artillery which could be acquired…