How Angela Merkel’s open borders roiled Europe and undermined her

Across the chancelleries of Europe, a realization is dawning. It began at the outskirts of the continent and has now made its way to the heart of Angela Merkel’s government in Berlin. It is the realization that even Merkel is mortal.

For the entirety of this century so far, Merkel has been a constant. She has been leader of the Christian Democratic Union (CDU) since 2000, when she publicly turned on her former political mentor, Helmut Kohl, over a party-funding dispute. And she has been chancellor of Germany since 2005, when she managed to put together a coalition with the left-wing …