“Amodern day mass migration is taking place … that could change the face of Europe’s civilization,” warned Hungarian PresidentViktorOrban.”If that happens, that is irreversible. … There is no way back from a multicultural Europe,” said Orban. “If we make a mistake now, it will be forever.”

Orban acted on his beliefs. He erected a 110-mile fence on the Serb border, redirecting hundreds of thousands of migrants away from Hungary to Croatia, thence to Austria and Germany.

Sunday, after a third of a million had passed through, Croatia replaced a center-left with a rightist party. A fortnight ago, the right-wing eurosceptic Law and Justice Party won a landslide victory in Poland.

Support for Angela Merkel, who has opened Germany to a million migrants, is plummeting. Bavaria’s CSU, sister party of Merkel’s CDU, is in rebellion. Bavaria has been the main port of entry for the hundreds of thousands of arriving migrants.

Europe is undergoing the greatest mass migration since World War II, when 14 million Germans were driven out of Prussia and eastern Germany and Central and Eastern Europe.

That mass migration halted after two years. But no end is in sight to the migrations from Africa and the Middle East.

As long as Europe’s borders remain open, they will come. And the people who wish to come number not just in the millions but the tens and scores of millions. And they know how to get there.

The routes — through Turkey to the Balkans on land, or across a few miles of the Med to the Greek islands, or from Libya to Lampedusa and Sicily, or into the Spanish enclaves on the Moroccan coast, or out to the Canary Islands — are arduous but not impossible.

Why should they not come?

Why should Arabs and Africans not flee the tyranny, terror, poverty and war that are their lot to come to Europe, live the good life, and have life’s necessities provided for their families by the munificent welfare states of northern Europe? And what is to stop them?

Jean Raspail’s “The Camp of the Saints” is proving more prophetic than Aldous Huxley’s “Brave New World” or Orwell’s “1984.”

Considering the crises facing Europe, the question is no longer: Will the EU survive? It is Orban’s question: Will European civilization survive the century?

This year, the EU monetary union, the eurozone, avoided breaking apart because Athens capitulated and accepted austerity, and the hard-bargaining Germans agreed to a bailout.

How long will Greeks and Club Med members of the EU accept austerity? How long will Germans bail out nations whose people like to work fewer hours while enjoying superior social benefits?