One morning in 1972, the French author Jean Raspail was at his home on the Mediterranean coast when he had a vision of a million refugees clamoring to enter Europe.

“Armed only with their weakness and their numbers, overwhelmed by misery, encumbered with starving brown and black children, ready to disembark on our soil,” he wrote. “To let them in would destroy us. To reject them would destroy them.”

At the time Raspail was a respected writer best known for his travelogues. But the racist novel that resulted from that episode, “The Camp of the Saints,” would become his most famous, most controversial and, surprisingly, most influential work.

For some 30 years, “‘Camp of the Saints’ has been one of the top two books in white supremacist circles,” said Heidi Beirich, an expert on extremism at the Southern Poverty Law Center. The center leaked emails earlier this month in which the Trump adviser Stephen Miller touted the book to Breitbart staffers as a work with strong parallels to recent waves of migration.

Published in 1973, the dystopian novel details how a flotilla of Indian migrants reach France’s southern coast to invade the country. Political elites fail to respond to the influx, and the continent is overrun. For nearly half a century, the book has stoked fears of immigration that have, to its supporters, seemed increasingly prescient as growing numbers of refugees and asylum seekers have arrived in Europe in recent years.