Should the United Kingdom go through with its withdrawal from the European Union, one of the most severe unintended consequences will probably be the exodus of a significant share of top professionals from London.

In fact, Paris, Frankfurt, Dublin, Amsterdam, and other cities on the Old Continent are already competing to attract UK-based bankers, doctors, architects, and academics.

Such “brain drains” are common in history. But never before has an established democracy experienced a catastrophic loss of human capital during a period of peace and prosperity. Usually, it takes a sudden regime change, violent conflict, or dire economic conditions to send a country’s professional elite fleeing en masse.

For example, many intellectuals have left Turkey in recent years as a result of President Recep Tayyip Erdoğan’s increasingly authoritarian government. In Greece during the sovereign debt crisis, high-skill workers were driven out by the lack of economic opportunity. And in Nazi Germany, Jews and other gifted but oppressed minorities were forced to seek refuge abroad.

No two mass emigrations are ever the same; but, to understand what is in store for London, the Brexiteers could still learn something from history.

With all due caveats, Brexit might well end up resembling Louis XIV’s decision to drive the Huguenots out of France, thereby condemning Paris to economic backwardness and political isolation for decades.

Under the 1598 Edict of Nantes, the Huguenots had been granted freedom of worship and civil rights as a Protestant minority in Catholic France. Owing to their strict Calvinist ethics, they were indefatigable and diligent workers, and they tended to occupy the most skill-intensive professions of the time (including silk-weaving, gold- and gunsmithing, printing, and watchmaking).

But in 1685, Louis revoked the Edict of Nantes, and the Huguenots gradually left France to join other Protestant communities across northern Europe.

As with Brexit today, European states rushed to attract the qualified workers that France had scared away. Within a week of the Revocation, the Elector of Brandenburg issued a decree formally inviting the Huguenots into his territory, while the Netherlands tempted them with the promise of immediate citizenship and tax breaks for three years.

Eventually, around 150,000 Huguenots settled in the Netherlands, Sweden, Prussia, and Ireland, and another 50,000 found their way to the UK. As is often the case in elite brain drains, their small numbers belied the enormous socioeconomic impact they would have.

While the French economy struggled for decades, Britain capitalized on the Huguenots’ talents to become the world’s first industrial powerhouse. One member of the Huguenot exodus from France, Denis Papin, invented the precursor to the steam engine.

And many others helped fine-tune the techniques that would turn British weaving, printing, and architecture into cutting-edge, world-leading industries.

Today, the world is once again on the cusp of an industrial revolution, and top professionals are on the march. It is widely understood that the countries with the highest-skilled workers and the most brainpower will have a significant advantage in the twenty-first century technology race.

In the case of Brexit, northern European countries are once again hoping to capitalise on a sudden flight of human capital in their neighborhood. France, ironically enough, could finally make up for the unnecessary loss of talent that it suffered three centuries ago.

The similarities between Brexit and the Revocation of the Edict of Nantes do not stop there. Both episodes epitomize their eras’ defining political conflicts. Whereas the political fault line in Europe three centuries ago was between Protestants and Catholics, today it is between those for and against the European project.

The emigration of the Huguenots and the impending exodus from London should be understood as side effects of political miscalculations made in the course of larger ideological battles.

For Louis, the persecution of the Huguenots was in keeping with his vision of a Catholic Europe — a vision that had been reinforced by the ascension of his ardently Catholic cousin, James II, to the English throne. Thus, rather than ordering the exile the Huguenots, Louis actually introduced strict emigration bans to prevent their departure, with the goal of forcing their conversion to Catholicism.

But rather than convert, the Huguenots fled. And, once abroad, they fomented the ire of European Protestants against France. After James II fell to the Glorious Revolution of 1688, the Dutch stadtholder William III, the Prince of Orange, acceded to the English throne, where he forged a coalition with Hapsburg Austria and various German Protestant states to engulf the French in a series of religious wars.

Back in June 2016, the Brexit referendum seemed to provide Britain with an opportunity to abandon a crisis-prone EU for a more dynamic Anglosphere. The Brexiteers had promised to put an end to low-skilled immigration from Eastern Europe, and that was what mattered most.

If top professionals left London, they would be viewed as acceptable casualties. From the start, Brexit has always been about intolerance of the “other”.

But, unlike the Huguenots, those now preparing to leave London are well-off members of the global elite. As such, their departure alone could immediately and abruptly erode the UK’s international status and influence.

French Protestants had to participate in a century of bloody religious wars to strike an equally powerful blow against their motherland.

It is never wise to stretch historical comparisons too far. But Britons would nonetheless do well to heed the words of the Duc de Saint-Simon: “The Revocation of the edict of Nantes, without the least pretext or any necessity, depopulated a quarter of the kingdom, ruined its commerce, and weakened it in all its parts.” Brexit will drive out fewer people, but the impact could be worse.

Edoardo Campanella is a Future of the World Fellow at the Center for the Governance of Change of IE University in Madrid.

Copyright Project Syndicate, 2019