A decade ago today, on 31 August 2015, Angela Merkel made the unilateral decision to open Europe’s borders. The rallying cry of the German Chancellor has gone down in history: ‘Wir schaffen das’ – ‘We can do this’. If we can’t, she added, ‘if Europe fails on the question of refugees, then it won’t be the Europe we wished for’. Merkel was motivated by conflict in the Middle East, notably in Syria and Iraq, but her invitation to seek refuge in Europe was seized on by many others. Of the estimated 1.3 million people who flooded into Europe in 2015,...