Not sure why one side is being described as British here by Andy? It was two Scottish armies in what was a civil war within Scotland in pre-union Scotland. Both sides were supporting someone who claimed the English as well as Scottish crowns. Nothing to do with one side being British. The Scottish Parliament awarded the throne to William & Mary and branded James a traitor. Dundee had been a chief henchman for James so had no option other than raise a rebellion. So you have a Lowlander leading an army of largely Highlanders and Mackay a Highlander commanding an army largely of Lowlander with some Highlanders. Nothing to do with British other than they were all on the island of Britain.