Allan, the history of the Battle of Otterburn, as I understand it, was that Percy was seeking redress for a previous skirmish when Douglas captured his banner whilst attempting to take the city of Newcastle. Percy followed him with around 8000 men but Douglas chose the better ground and, because it was a battle through the night, Percy couldn't use his archers. Anyway, despite being the victor, Douglas was killed, fulfilling his premonition:

"Last night I dreamed a dreary dream,
From beyond the Isle of Skye,
I saw a dead man win a fight,
And I think that man was I."