> Ireland wasn't exactly unified back then.
Mhm, but neither was Scotland when William Wallace popped up.
> Too many competing clans, as well as the integrated Hiberneo-Normans and the less integrated English settlers. During the war various Irish groups apparently drove back the Pale to around Dublin. Something will need to be done with the various supporters of the Wars of the Roses who had land in Ireland. Have them fall from grace, their armies destroyed in England, whatever. I feel the Geraldine/FitzGerlads might be a group to look into, if only for how the Cross of St. Patrick in the Union Jack comes from their cost of arms.
I'd imagine the Hiberno-Normans would be much the same as the Normans in Scotland (of which Wallace might have been one): Largely acceptable at this point in time.