which more or less means keep it Protestant,
Lonewolf I wont shout at you for being insensitive. It is understandable that from a transatlantic viewpoint you are bound to have a fairly simplistic view of what are quaintly known as "the troubles"
The forces of the crown did indeed spend much time and blood in Northern Ireland, but not to keep it Protestant, as you claim, but to keep it part of the United Kingdom, as was, and remains, the wish of the majority of the electorate of Northern Ireland. To imagine that the wishes of the population in this respect can be neatly divided between the Catholic and Protestant populations is naive - certainly most republicans were and are Catholics, but that is a very long way from stating that most Catholics are republicans.
My own son, fourth generation of a Roman Catholic family of Irish origin with a proud record of service in the British military wears the Campaign Service Medal, clasp 'Northern Ireland', and sees no contradiction in that. His first and only duty as a soldier in that conflict was to protect citizens of the UK from their enemies, whatever their religious persuasion.