In 2021, a hundred years after the creation of Northern Ireland, Boris Johnson tweeted: “Let me underline that, now & in the future, Northern Ireland’s place in the UK will be protected and strengthened.” Since the word “not” has to be inserted automatically into every positive statement Johnson makes, unionists ought to have taken this as fair warning: Year 101 of Northern Ireland’s existence would be its equivalent of George Orwell’s Room 101, where you are confronted by your own worst nightmares. After last week’s assembly elections, the unionist nightmare takes the amiable form of Michelle O’Neill, Sinn Féin’s vice-president and now putative first minister of the Northern Ireland executive. The source of dread is not so much O’Neill herself as the historic moment she embodies: Catholic nationalism outstripping Protestant unionism. Her party is dedicated above all to ending the union. It beat Johnson’s allies in the Democratic Unionist party (DUP) in first preference votes by eight percentage points. In a normal polity, the rise and fall of parties does not have existential implications. But Northern Ireland has never been normal. It was created to ensure one overwhelming imperative: to allow as many Protestants as possible to stay in the UK and exclude themselves from the emerging Irish state. Its border was drawn to create an area in which Protestants would have a permanent majority – which meant, of course, that its Catholic population would form a permanent minority. It’s been obvious for a long time that this bet on permanence, like every other such gamble in history, would ultimately be a losing one. The unionist political monolith crumbled in 1972, when Edward Heath, as prime minister, pulled the plug on its parliament in Stormont. From then on, it has been accepted that if Northern Ireland could be governed at all, it would only be through the sharing of power between nationalist and unionist parties. That arrangement was institutionalised by the Belfast agreement of 1998. In that sense, unionists have long since grown used to the reality that they would never again exercise power unilaterally. Yet they could still console themselves with the thought that, even if they had to accept equality with nationalists, they were first among equals. In some respects, this was a mere trick of language. The agreement designated the leader of the biggest party as “first minister” and of the biggest party from the other side as “deputy first minister”. This was bad drafting – the two offices have precisely equal status. But language and symbolism matter deeply in Northern Ireland and that unqualified “first” was a thick comfort blanket for unionism. It’s been ripped away now. Two big things happened in the election. One is that – because symbolism matters just as much on the nationalist side of the divide – the prospect of O’Neill becoming first minister drew some more Catholic voters away from the Social Democratic and Labour party (SDLP) and towards Sinn Féin. But the other is that Brexit continued its work of dividing and undermining unionism. This second factor was actually more consequential than the first. Sinn Féin’s share of the vote rose only modestly. But the significance of that increase was magnified by the DUP’s decline. In the assembly elections of May 2016, just a month before the Brexit referendum, the DUP took 29% of the vote. On Thursday, it got 21%. Its vote has dropped precipitously even though it had what ought to have been a trump card – the tribal fear that, unless Protestants voted for the DUP, Sinn Féin would win the election and proceed to push for a border poll on a United Ireland. (Ironically, while the DUP was playing up the alleged imminence of a border poll, Sinn Féin was careful to play it down and concentrated its campaign on bread-and-butter issues.) There is a very long history in Northern Ireland of holding your nose and voting for politicians from “our side”, not because you especially like them, but to keep the other crowd out. Why did this impulse not kick in this time? Because the Brexit revolution is devouring its own children. Apart from Ukip, the DUP was the only substantial party in the UK to be wholly and enthusiastically in favour of the hardest possible Brexit. It funnelled money into the leave campaign in England. Handed the balance of power at Westminster, it used it to help bring down Theresa May and install Johnson in Downing Street. And, remarkably for a party with a very high proportion of teetotallers, it got so drunk on the fumes of Brexit that it believed Johnson when he swore that there would be a border down the Irish Sea “over my dead body”. All of this made the DUP look foolish – admittedly not the most difficult achievement of the Brexit project. And it disturbed two very different groups of voters. One is hardline unionists who blame the DUP for having created, however inadvertently, the Northern Ireland protocol that keeps the region within the EU’s single market, even while Britain diverges ever further from it. Those people voted in significant numbers for the small Traditional Unionist Voice (TUV). The other alienated constituency is moderate Protestants who never wanted to be dragged out of the EU. They moved to the cross-community and pro-EU Alliance party. These developments raise two very big questions – the future of the protocol and a united Ireland. The first is clarified by the election. Put simply, if Johnson claims to be representing the people of Northern Ireland in using the protocol as an excuse to revive conflict with the EU, he is lying. The parties that oppose the protocol – the DUP, Ulster Unionists and TUV – got 40% of the vote between them. Those that support the protocol – Sinn Féin, the SDLP, Alliance and two small parties – got 55%. If the Tories follow through on Dominic Raab’s threat yesterday to take “whatever measures are necessary” to unilaterally alter the protocol, thus triggering a trade war with the EU, it will not be to honour the wishes of Northern Ireland’s voters. It will be a futile effort to save Johnson’s skin. As for a united Ireland, only a fool would think it’s coming soon – and only a bigger fool would think that it has not, in some form, come closer. It’s not coming soon because most Irish people have not really begun to grapple with what it might mean in practice. But the identity of Northern Ireland has been drastically altered by both the slow demographic change that has culminated in these election results and by the DUP’s embrace of Brexit extremism. The long and the short movements of history are coming together to create the sense of an ending. There is an urgent need to talk, in the most generous, open and imaginative way, about what Northern Ireland’s afterlife might look like and how everyone can find a place within it. Fintan O’Toole is a columnist with the Irish Times