It has been 1,225 days since British voters, amid an all-time-high turnout, voted by a four-point margin to “Leave” rather than “Remain” in the European Union. Now, it appears that a general election set for Dec. 12 will finally help Britain escape from the EU’s “ever-closer union.”

The issue is unfamiliar to most Americans, yet the political cleavages it has caused closely resemble our own. American foreign policy elites have long encouraged European unity, on the sentimental principle that it worked well for us in 1776 or the now-long-obsolete argument that it would prevent another cataclysmic war between Germany and France.