The solution will have to be political. Enough has been done in Ireland in the name of "morality". :/
Eventually the island will be united, because there is more to unite the nation than to divide it, but the process will be long, and they will have to discover it themselves.
If the British must stay to minimize the militias' damage to the rest of the people while the process grinds on, so be it. The militias are there because of them. It's only fair that they should bear the burden of dealing with them.
It would go a long way if the British would learn how to apologize and how to treat those not like themselves as people with dignity. Perhaps that will happen too. Ah, well. First occupied, last evacuated.