What to make of the stunning electoral breakthrough of Germany's AfD? If the party has indeed cohered around opposition to Angela Merkel's open-door refugee policy, then Euro-Cassandras like Douglas Murray were right all along. Western European leaders' indifference to mounting public concern about mass immigration first inflamed the unity crisis in the E.U., and has now sparked the rise of a right-leaning party in a country about which—historically speaking—the world has good reason to worry. Chancellor Merkel has drawn exactly the right conclusion, if only belatedly and with typical understatement. "AfD presents an extraordinary challenge for Germany. We need to listen to their voters."