At the Belgrade airport we were told we could drive our Serbian rental car anywhere in eastern Europe – except Kosovo. But Kosovo, I noted, is not on the map. That’s because it is part of Serbia, said the Hertz man, as he sketched its approximate borders with his pen. Then how will we know when we get there, I asked? Oh, you’ll know, he said. They’ll stop you. They don’t like us very much. For DeWitt Sage, a documentary filmmaker, and I, who have come here to try to comprehend the refugee situation threatening to overwhelm Europe, it was a jolting reminder that the Balkans, which is now the pathway for refugees fleeing by the hundreds of thousands from Syria, Afghanistan, Eritrea and elsewhere, was not long ago itself the scene of brutal ethnic warfare – of sieges, bombardments and genocidal executions that unleashed centuries of hatred in what seemed an endless war. In 1999 NATO air forces bombed Novi Sad, the city on the Danube where I write, so massively that it took four years to restore the river.

It is a reason for hope that peace, however fragile, has returned to the Balkans less than two decades later; and it is a reason for despair that this area is now the passageway to Europe for those fleeing atrocities so horrific they seem unprecedented in their scope and barbarity.

What it is not is a passing phenomenon. According to the UN Refugee Agency, 42,500 people are forced from their homes every day. They will go somewhere.