When he was traveling the world, for his law firm and as an informal world ambassador, George Mitchell often spoke of the commonalities he found in people on all continents, among all religions, nationalities and ethnicities.

Parents want the same things for their children, he said: a good education, health care, good jobs — and an absence of violence, in the community and nation.

Mitchell had credibility, for he brokered, sweated through, and managed the Good Friday accord that brought peace to Northern Ireland in 1998, and an end to the intermittent warfare that plagued an entire generation.

The Good Friday agreement, which should last at least as long as “The Troubles” that preceded it, has endured beyond expectations.

Peace never seems to sell newspapers like wars and political conflict, but may be more important — a point to remember in our own conflict-filled moment.

Across the Atlantic, Northern Ireland’s peace is having consequences more profound than anyone predicted when signed by leaders of the Social Democratic and Labour Party (SDLP), led by John Hume, and the Ulster Unionist Party (UUP), led by David Trimble.

The SDLP was the moderate Catholic, or Republican, party, while the UUP played the same role for Protestant Unionists.

Hume and Trimble shared the Nobel Peace Prize; Mitchell was unaccountably left out. Neither leader played a large role in the coalition governments that followed.

Today, the largest Catholic party is Sinn Fein, once the political arm of the Irish Republican Army (IRA), governing in coalition with the Democratic Unionist Party (DUP), founded by Protestant firebrand Ian Paisley.

Parliamentary elections are set for May, and — unthinkable a generation ago — Sinn Fein could form the next government. Support for the DUP has plunged.

The reason, in a word, is Brexit — the curious decision by voters of the United Kingdom of Great Britain and Northern Ireland (and Scotland, and Wales) to cut ties with the European Union (EU) in a 2016 referendum nearly simultaneous with Donald Trump’s election.

Trump is out of power, but Boris Johnson, the “genius” of Brexit, was apparently thriving as prime minister, routing the opposition and leaving the once-formidable Labour Party with rump status.

Johnson is a curious mixture — a Conservative trained at Oxford and comfortable in the highest circles, but presenting a rowdy, wild-haired appearance and “common man” theatrics. Like Trump, he makes it up as he goes along.

Johnson is now in serious political trouble, with two-thirds saying he should resign. It’s all about — or apparently about — boozy parties at Downing Street, the prime minister’s residence and office, during the height of pandemic shutdowns.

The tempest has been rising, and subject to an official, but independent, investigation — seemingly a bit less substantial than our Jan. 6 committee.

What it’s really about, however, is Johnson’s bungling of Brexit, in which, despite his bluster, Europe holds all the cards.

Johnson made promises he couldn’t keep. Famously, the former journalist wrote two op-eds before the Brexit vote, one for “Remain,” and the other for “Leave,” then running “Leave,” since it seemed to be winning.

Initially, both Conservatives and Labour straddled the issue that split both parties; Johnson emerged as the decisive leader, and swept the 2019 parliamentary elections.

Yet he was always trying to square the circle. The Good Friday agreement specifies there can be no customs border between the Republic of Ireland, comprising most of the island, and the six counties of Northern Ireland.

It’s enshrined in the EU charter, and Johnson knew he couldn’t change it. Yet he promised the DUP that, somehow, there wouldn’t be a customs border between Northern Ireland and the rest of the UK.

Brexit went ahead, and goods that once moved freely across the Irish Sea are subject to inspection, fees and delays, crimping the economy.

Johnson was charming English voters, but not fooling those in Northern Ireland, who rightly feel betrayed.

We’re a long way from resolution, but one can foresee the day for another referendum — one uniting Ireland, north and south, within the EU, bidding the UK goodbye. Already, demographic shifts have made Catholics and Protestants equal in the North; the benefits of EU membership are tempting.

If that occurs, the Scottish National Party could force another referendum on independence. Scotland voted overwhelmingly against Brexit, and could thus rejoin the EU.

That would leave to Boris Johnson’s successor the United Kingdom of England and Wales, where things were in 1607, four centuries ago.

Americans occasionally yearn for the clear lines of Britain’s parliamentary government, as opposed to our own divided powers.

Yet the election of Donald Trump may have only short-term consequences. Brexit could be far more lasting.

Douglas Rooks, a Maine editor, commentator and reporter since 1984, is the author of three books. His first, “Statesman: George Mitchell and the Art of the Possible,” is now out in paperback.  He welcomes comment at drooks@tds.net