Read: The Good Friday Agreement in the age of Brexit

But other barriers have come down. The customs and security border between Northern Ireland and the Republic in the south has vanished. People who live on the island of Ireland cross the border to work, to shop, or to visit a doctor as easily as Americans cross state lines. Vehicles cross the border an estimated 30 million times a year, slowed only by traffic. A retired senior official told me of rural milk routes in which a truck will cross the border 20 times in a day as it transits from farm to farm. The hospital in Londonderry is funded by the EU to serve Irish people across the line in Donegal, on the same basis as National Health Service patients of British nationality.

The currency differs on the two sides of the border. So do the cellphone carriers. VAT rates diverge. Ireland is not united. But Irish people can live as if it were, if they wish—or not, if they don’t wish.



That partnership applies not only on the island of Ireland, but on both sides of the Irish Sea. Ireland-bound mail from beyond the EU is processed in the U.K., sparing Ireland the need to inspect for drugs or explosives. Irish beef, cheese, and mushrooms are sold in British supermarkets within hours of being packaged on the other side of the water.

Would-be criminals and terrorists are policed by services that cooperate as intimately as if they served only one sovereign. Britain and Ireland have found a way to be one marketplace, one travel area, one energy grid, one food emporium, one security partnership—while maintaining two independent political systems, two distinct historical and cultural narratives.



All of this could have been done without the European Union, but the existence of the European Union hugely lowered the inhibitions against doing it, especially on the Irish side.

Read: How Brexit threatens peace in Northern Ireland

When Ireland complies with a European arrest warrant, or imports gas via the EU-regulated pipeline between Britain and Ireland, or shares data governed by common privacy laws, or raises and slaughters beef according to the exact same standards prevailing across the Irish Sea—it can do all those things without any sense of domination by a historically oppressive neighbor. It is doing so within a context whereby both the stronger and the smaller country have pooled their sovereignty with two dozen other countries, and within which both the stronger and the smaller partner daily discover that they have much more in common with each other than either does with its fellow EU members across the water.



It was an Irishman, James Joyce, who wrote the phrase “History … is a nightmare from which I’m trying to awake.” Those words could have come as easily to a Pole or a Catalan. From 1968 to 1998, 3,500 British and Irish people died violently, and perhaps 50,000 were wounded. As in Alsace-Lorraine and West Prussia, as in Iberia and Italy, in Ireland, the Anglo-Irish Good Friday Agreement (and the successor agreements built upon it) seemed to show that “Europe” could bring peace by building new identities to encompass and reconcile murderous, ancient quarrels.



After the Brexit vote, British politicians insisted that nothing need change on the island of Ireland. That promise will be extremely difficult to honor. What happens when Afghan refugees in Germany start flying to Dublin, taking the bus to Belfast, and flying from Belfast to work in London? The Irish border is bound to harden. Perhaps at first it will be only cameras. Based on past experience, cameras will be cut down and destroyed by offended nationalists in the border area. So the border will have to be manned. The border guards will become targets. Even today, with both Ireland and the U.K. in the EU, criminal gangs exploit arbitrage opportunities. (Ireland lightly taxes diesel fuel sold to farmers. The fuel is dyed red to identify it. Criminal gangs have learned to bleach the dye and smuggle the cheap fuel into Northern Ireland.) As those arbitrage opportunities multiply, so will the criminal gangs. Many gangsters began as IRA paramilitaries. They have kept their weapons—and even sometimes their ideology.



Sooner or later, a border guard will be shot at.