Police officers detain an opposition supporter during a rally in Vladivostok, Russia.Yuri Maltsev / Reuters

MOSCOW— It’s not a rare sight in this city to see tens of thousands of people pour into the streets to express their opposition to the government that makes its home here. Moscow was the epicenter of the massive pro-democracy protests of 2011-2012, and many others since, including rallies to commemorate slain opposition leader Boris Nemtsov. This is the city where Vladimir Putin lives, along with the tens of thousands of people who make his machine of state hum. But given its wealth and cosmopolitanism, Moscow is also the most oppositional city in Russia. In 2013, it nearly forced the Kremlin-installed mayor into a run-off with a charismatic young opposition leader, Alexey Navalny. So in some ways, it was not surprising to see thousands heed his call to come out and protest here on Sunday.

But Sunday’s protest was different. Unlike the rallies in Nemtsov’s memory or even the 2011-2012 protests, this one did not have a permit from the Moscow city authorities. Over the weekend, the mayor’s office warned people that protestors alone would bear the responsibility for any consequences of attending what they deemed an illegal demonstration. But despite those warnings and despite the fresh memory of some three dozen people being charged—many of whom did prison time—for a protest in May 2012 that turned violent, thousands came out in Moscow. The police estimated attendance at 8,000, but given officials’ predilection for artificially deflating the numbers of those gathered at such events to make them seem less of a threat, the number could easily have been double that. People clogged the length of Tverskaya Street, one of the city’s main drags. The iconic Pushkin Square was packed, and people clung to the lampposts, chanting “Russia will be free!”

Three weeks ago, Navalny, who became famous as an anti-corruption blogger, posted an hour-long video exposé (with English subtitles) on his blog and YouTube channel. It showed, in great detail and using drone footage, what he said were the vast real-estate holdings of prime minister and former president Dmitry Medvedev, a man who talked of fighting corruption during his presidency and who in May told the residents of recently annexed Crimea, who are suffering from electricity and fuel shortages, “We don’t have the money now. ... But you hang in there!” The money, Navalny alleged, was all bundled up in palaces, some costing hundreds of millions of dollars, all over the country. It was strange to attack Medvedev, now a widely ridiculed has-been in Russian politics, and many doubted that Navalny telling people to go out and protest Medvedev would have any resonance. And yet, when he named the day—March 26—people across 11 time zones answered his call and came out.

What was most remarkable, though, was that the protests happened not just in protest-loving Moscow, but in over 90 cities across the country. People came out by the hundreds in Vladivostok, in the Far East; in Siberian Tomsk; in Krasnodar, in the south; and in Kaliningrad, a tiny Russian enclave between Poland and Lithuania. They came out in cities like Chelyabinsk, in the Ural Mountains; southern Samara; and in Novosibirsk. (Meduza, an independent Russian news outlet, has a compelling photo essay here.) This is significant because “the regions,” as everything outside of Moscow and St. Petersburg is known, are significantly more conservative and Putin-friendly than the two biggest cities. They are much poorer, much less developed, and people living there are often more dependent on the state to make their living. There is almost no independent media there, except what can be found online, and information critical of the government can be hard to come by. Going against the authorities can result in serious repercussions, both economically and in terms of personal safety, sometimes more so than in Moscow, where people have more money, political connections, and the savviness to solve their problems.

The fact that thousands and thousands in areas outside of Moscow and St. Petersburg came out despite this tremendous risk, to participate in rallies that were, with few exceptions, not permitted by the authorities, means a few things, and none of them are good for Putin.

First and foremost, it was a tremendous show of power by Navalny, who has declared that he is running for president of Russia in 2018. He is a long shot at best, and the Kremlin may not even allow him on the ballot. Yet he showed he has real political power and that tens of thousands of people across the country see him as a legitimate leader, despite the Kremlin’s assiduous work to marginalize him by keeping him off government-controlled television—still Russians’ main source of news—and inventing a half-dozen criminal cases against him.

Second, it indicated that despite the government’s total control of television and creeping control of the web, technology and social media are still powerful tools. By Sunday, the Medvedev expose had been viewed nearly 12 million times. By comparison, 52 million people voted in September’s parliamentary elections. It doesn’t mean that all those viewers believed it or agreed with its anti-Kremlin message, but it means they at least saw it, even though it wasn’t shown on state TV. It also means that Navalny, with his YouTube channel, which was doing a live broadcast during the protests, can reach past Kremlin TV and influence people even in the heart of Putin country.

Third, it indicated that, despite the slight easing of the economic crisis in Russia and the conventional wisdom that Russians have adjusted to the slow sagging of their economy, an economic, populist message resonated enough to bring out what in Russia counts as a massive showing. Because the economy may not be at rock bottom anymore, but it is still bad. Since the economic crisis began in 2013, Russia’s GDP per capita has plummeted—from $15,500 to $9,000—and it is now approaching that of China’s. In 2013, it had been double China’s.

Fourth, despite the government’s efforts to provide a “patriotic”—that is, pro-government—education to young people, to sponsor various Kremlin youth groups, and to intimidate students in schools and universities into not attending such events, a huge number of those who came out Sunday were very, very young. The hero of a protest in Tomsk was a grade schooler who addressed the crowd. Many of those I spoke to in Moscow were younger than 21. Some were as young as 15, and, though they don’t remember the 2011 protests, they are old enough to have ideas about how they want to live. “For a country that is so rich in natural resources, we are too poor,” Andrei, 16, told me. And as the police made thousands of arrests across the country—there were over a thousand in Moscow alone—they arrested the minors, too, like this kid with his bike. Or this one, who looks barely pubescent but clearly in pain as police twist his arms behind his back. They packed them in paddy wagons with the adults and detained them for hours.

The Kremlin is already fighting back. Kremlin TV didn’t show the protests at all, and on Monday morning Putin’s spokesman said that those minors had been promised money by some shady actors to be paid if they got themselves arrested. Many of those who work in Navalny’s Anti-Corruption Foundation, which made the expose, spent the night behind bars. The police raided their offices and seized all their computers. Navalny’s campaign manager, Leonid Volkov, is being charged with a criminal offense—inciting hatred during his Sunday broadcast on Navalny’s YouTube channel. Navalny himself was sentenced to 15 days in jail by a judge who wouldn’t let him call a single witness in his defense. Because he is on probation for yet another trumped up conviction, the most recent charges could eventually land him in jail for years. Meanwhile, the authorities immediately opened up a criminal investigation when a policeman who was attacked in Moscow landed in the hospital with a head trauma. All of this could send another few dozen protestors to jail for a long time, just like what happened after May 2012.

But intimidation and jail sentences are a short-term fix. And Sunday showed that they have a very limited effect. Monday, as Moscow courts rushed to process the hundreds and hundreds of arrests, the Moscow opposition struggled to process what had happened. Like the protests that exploded on their streets five years ago, these were an unexpected breach in the façade of indifference and acceptance that the Kremlin had worked so hard to erect. Behind it, though, something had clearly changed.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.