The north of Ireland is not Unionist, Nationalists hold a majority in Ulster, which would be considered the 'northern' part of the country.
The country did not go to war with each other, two factions of the IRA and IRB split, they both had the same ideals and aims, just a different way of doing it, if as a result the Anti-Treaty side forced British troops out of Ireland, the pro side would have been forced to come into line by their supporters, and visa versa.
Do the British army not do the same thing? As LazyHippy said, one mans terrorist is anothers freedom fighter, I believe that the IRA have always had a legimate purpose and that is to remove British rule from my country.
You are correct however, we are digressing from the point at hand, Ted Kennedy was a good man, RIP.