No More English!

What is it?
It is an alternate timeline in which after the execution William le Scrope, 1st Earl of Wiltshire also last King of Mann (In our timeline) a manx man of the age of 25 leads a rebellion against the English and of course wins; but what does it cost him?

What are the plans?
So far just to figure out who; with; and how the young manx man wins the Manx War of Succession.