Hector Munro was also made constable of Strome Castle on behalf of the MacDonnells of Glengarry by King James V. Previously Ewen Cameron had been constable of Strome Castle for the MacDonalds of Lochalsh.
The MacAuleys and MacPhoils arrived mid-way through the battle, and had planned on siding with the McQuillans and O'Neills, but the chief of the clan was persuaded by Sorley Boy MacDonnell to join forces with the MacDonnells.
Attempts were made by Thomas Radclyffe, 3rd Earl of Sussex, Lord Lieutenant of Ireland, to expel the MacDonnells back to Scotland.
He waited at Glenfinnan for a number of days as more MacDonalds, Camerons, McPhees and MacDonnells arrived.
The MacDonnells, Irish cousins to the Macdonalds offered to sail to Scotland to serve the King, hoping to use the conflict to gain their homes back as a reward if the Royalists won.
Supported by Munster and Connacht, and assisted also by English contingents and by the MacDonnells of Antrim, O'Neill took the castle of Ballyshannon, and after devastating a large part of Tyrconnell he encamped at Knockavoe, near Strabane.