In Poland, last weekend’s independence day celebrations mutated into perhaps the ugliest international congregation of the extreme right seen in Europe in recent times. The grotesque procession of militant nationalists, white supremacists, and radical Islamophobes included Poland’s National-Radical Camp, the National Movement, and the All Polish Youth, as well as the deputy chairperson of Jobbik, Hungary’s most xenophobic party. These groups and others who attended trace their ideas back to anti-Semitic, sometimes-fascist movements popular before World War II. Like their forebears, they won’t rule out the use of violence.

The march cast a disturbing light on the militant and radical currents coursing through Europe’s ever-more successful nationalist parties, for whom Hungary’s governing Fidesz party is a model. Its members include Poland’s ruling Law and Justice (PiS) party, Alternative for Germany, and the Austrian Freedom Party, among many others. Their polished images and relatively temperate language have enabled them to post record numbers at the ballot box of late—and, indeed, to jar Europe’s liberal order by pushing their policies on three areas in which their interests overlap with neo-Nazi extremists: immigration, Islam, and the EU.  

Not all of the estimated 60,000 people who took to the streets on Saturday were sympathizers of the far right, or even of PiS. But the old-school extreme right, unapologetic fascists among them, was on full display, emboldened by the impressive electoral showings of Europe’s national populist parties, most recently in Germany, the Czech Republic, and Austria. The radicals turned what could have been a civil celebration of Poland’s return to statehood in 1918 into a fierce exhibition of hatred and intolerance.

In contrast to the professional politicos who crave respectability and votes, the  figures who marched on Saturday wore masks, flashed white-power insignia, and screamed “Pure Poland, white Poland!” and “Refugees get out!” One banner on display read Pure blood, Clear mind; another read Europe will be white or uninhabited. Marchers waved giant Polish flags and set off smoke bombs and flares that blanketed the procession in clouds of red smoke. The rightist parties—distinct from the mob—need the energies and numbers of the extremists to keep their base alive and engaged. But that  comes with enormous risks, ones that Europe knows well.

Poland, led by the arch-conservative nationalist PiS party, is on the front lines of Europe’s shifting political landscape. The government’s refusal to condemn the march—the interior minister even called it “a beautiful sight”—is emblematic of the new zeitgeist in parts of Europe. Obviously the radicals knew they were safe in Poland. Two days after the march, Polish president Andrzej Duda, not a PiS member, condemned the xenophobia and racism, saying there’s no place in Poland for “sick nationalism.” But, incredibly, the PiS government wouldn’t budge.

“The groups on the streets in Warsaw espouse the most extreme ideology in Europe today,” Peter Kreko, director of the think tank Political Capital Institute in Budapest and an expert on Central Europe’s far right, told me. “They see Christian Europe and their own nations in apocalyptic terms, as being overrun by Muslims and other immigrants, and ruined by the EU.”

While the rightist parties and the radical streets movements are not one and the same, their paths overlap as do their strategies. The government’s official slogan for the event was “We Want God,” lyrics from a Polish song that President Donald Trump quoted this summer while in Poland. (Trump lauded Poland for defending Western civilization, presumably a reference to its role in helping oust the Ottoman Empire from Europe in the 17th century and defying the Soviet Union during the Cold War.) In Warsaw and elsewhere, marchers—militants as well as ordinary burghers—chanted "God, honor, country," reflecting Poland’s own brand of Roman-Catholic-inflected nationalism.

Pro-government media outlets like the website wPolityce.pl defended the event. “Of course, if someone is bent on doing so they can depict the independence march as a gathering of fascists,” one of its bloggers wrote. “Crowds chanting patriotic slogans, national flags, the odd firework—this is a dreadful spectacle for the left-liberals who advocate multiculti values. [But] a positive message was discernible. The participants want a Catholic Poland that respects its own traditions and culture.” TVP, a government-friendly station, described it a “great march of patriots.”

“Populist parties like Fidesz and PiS use the mob to promote their goals,” Kreko said. “The strong, negative enemy images mobilize the masses by blurring the boundaries between the mainstream right and the extremists.” Moreover, he points out, populist parties like PiS and Fidesz need to show they have the backing of the masses to legitimate their populist credentials as the true voice of the volk. “It’s a risky business for the electoral parties but they have to rely on the radicals for their numbers,” he said.

The rally drew condemnation across Europe. Some observers drew parallels with Europe of the 1930s, when underground fascist movements nurtured and empowered extremist politicians. Poland’s liberal media outlets, like the opposition daily Gazeta Wyborcza, claimed the event reflected the “fascistic” metamorphosis of public life in Poland under the PiS leadership, which has been starkly criticized in the EU for authoritarian reforms and arch-conservative social policies.

Just as unnerving was the march’s international scope: In attendance were extremists from Italy, Sweden, Hungary, Slovakia, the U.K., and elsewhere. (Originally, the American white supremacist Richard Spencer was invited to speak in Warsaw the day before the march. Poland’s government expressed “opposition” to his visit, and he cancelled his plans to attend.) Paradoxically, the ultra-nationalists conceive of themselves as an international, pan-European  front. They seem to believe that there’s much to be gained through cross-border cooperation—especially when borders themselves aren’t the issue—for now at least. The extremists are united in their hatred of the EU, which they claim shackles their sovereignty and suppresses the original spirit of the continent’s ethnic nations. The EU, they realize, isn’t going to be overthrown by one country alone, but by many—and perhaps even at the ballot box.

In every country where Europe’s far-right parties are ascendant, they act in loose conjunction with radical, often thuggish circles in their vicinity: groups that often take the parties’ carefully chosen words, their veiled racism, to their logical conclusion—namely, violence against foreigners or minorities like the Roma. The militants may not stand on the same podium as the politicians, but the parties are content to allow the garish displays of the mob grow into spectacles like the one in Warsaw in order to rally support and draw attention. But the parties intent on joining coalition governments, from Austria’s Freedom Party to Slovakia’s National Party, don’t control the violent radicals. They can’t keep them from burning down refugee hostels or ransacking Roma villages—crimes that hopefully, the polite, well-coiffed populists don’t condone.

Whatever support the mob gives, it can take away, too. And one day it is sure to—when the made-for-TV political parties show themselves too timid and reluctant for their tastes. It is then that they will finally be forced to reckon with the violent furies they have stoked.