As in the Republic, politics in Northern Ireland are not organized along a left-right scale. The overriding issue here is the constitutional one: should Northern Ireland be a part of the UK, or be part of a reunited Ireland. Those who wish to reunite with the Republic of Ireland are called nationalists, and there are two major nationalist political parties, Sinn Fein and the Social Democratic and Labor Party (SDLP). Those who favor union with Great Britain are referred to as unionists, and although the unionist bloc is more fractured than the nationalist one there are also two major parties here, the Ulster Unionist Party (UUP) and the Democratic Unionist Party (DUP).
One cannot really understand politics in Northern Ireland, or the six counties as many nationalists call it, without having a fairly good understanding of Irish history. One really should go all the way back to the Ulster plantations of the early 1600s, when the British monarchy confiscated vast amounts of land from the native Irish in the northern region known as Ulster and gave it to Protestants from Scotland and England. This created a Protestant settler class in Ulster, whose descendants are today's unionists. This class, loyal to and dependent on Britain for the maintenance of its privileges, was used by the British to assist in maintaining their control in Ireland.
The success of the Ulster Plantation resulted in the division of Ireland in 1921, when Britain and the Irish Republican Army (IRA) negotiated a settlement to the war for independence. Ulster's Protestants were as loyal to Britain as ever, and were terrified of becoming part of an independent Ireland and losing their dominant status. For its part, Britain knew that if it could maintain control of Ireland's industrial northeast it could maintain virtual control of the rest of Ireland, heavily agricultural, through economic means. Thus they invented the province of Northern Ireland, drawing it to include as much territory as possible and still have what was felt to be a permanent unionist majority. Michael Collins, negotiating on behalf of the IRA, agreed to this division in exchange for a measure of self-rule for the rest of Ireland, feeling that Northern Ireland was not a viable entity and that this treaty would merely be a stepping stone to a united and fully independent nation.
The nature of this new province of Northern Ireland was made clear by one of its first Prime Ministers, who called it "a Protestant state for a Protestant people." Catholics were legally discriminated against in housing, jobs, benefits, voting, and were in every respect considered second-class citizens. Britain left the unionists to rule pretty much as they pleased, while enjoying the dominance of all of Ireland that was given to them through control of the north's industry.
