Navalny, the New Sakharov

July 19, 2013 will go down in the history books as a milestone in the fight for democracy in Russia. It was a dramatic day. It began with the authorities' attack on civil society and ended with their retreat on all fronts.

In Kirov at 12:20 p.m., after a trial marked by numerous procedural violations, opposition leader Alexei Navalny, who is running for the Sept. 8 mayoral election, was convicted of embezzlement and sentenced to five years in prison. Navalny and his co-defendant, Pyotr Ofitserov, were taken into custody in court and transferred to jail.

On Saturday, the cheering crowds in Moscow greeted Navalny with the same joy that a previous generation met human rights activist Andrei Sakharov when he returned to Moscow from internal exile in 1986.

The first reaction to the sentence was a tumble on the Russian stock markets. Within an hour, the RTS fell by 1.6 percent, and the MICEX fell by 1.8 percent. The Russian Internet was deluged by thousands of angry posts, and by evening tens of thousands of demonstrators took the streets in Moscow, St. Petersburg and 21 other Russian cities.

In Moscow, thousands of people gathered at a central intersection by the Kremlin and blocked traffic along Tverskaya Ulitsa several times. They chanted slogans and plastered the first floor of the State Duma with pro-Navalny stickers.

The authorities seem to have been caught unprepared by the scale of the reaction, and they took an unexpected step back. After the demonstrations had begun, the prosecutor's office protested the decision to take Navalny and Ofitserov into custody and requested that they be released until their appeal. Even the prominent lawyer Genry Reznik was surprised. "I don't recall another case when the prosecutor's office objected to the court's custody decision after a conviction."

But in the center of Moscow, where the telephone lines were overloaded and mobile Internet was apparently jammed, information reached the protesters later. The demonstrations continued. The police arrested about 200 people. They were quickly released, and many returned to Tverskaya. Groups of protesters roamed the city streets all night, organizing impromptu sit-ins. The following day, a shocked Navalny was taken from his cell, where he'd spent the night in isolation, brought back to court, placed in the glass cell in the courtroom and was told that he was released until the decision of the appeal's court. On Saturday, he and Ofitserov returned to Moscow by overnight train.

"I never could have imagined that in two days I'd be at Yaroslavsky Station again," Navalny told the thousands of supporters who came to greet him. "Forgive me for not believing in you enough."

The rapid and unprecedented measures taken by the authorities gave birth to dozens of conspiracy theories. United Russia Duma deputy Yevgeny Fyodorov told the Internet channel Poznavatelnoye.tv in all seriousness that Navalny was released after U.S. President Barack Obama called the lead prosecutor in the Navalny case.

But the most popular theory was that Navalny was released so he could run in the Moscow mayoral election on Sept. 8. Navalny, the theory has it, would only take a small percentage of the votes, which would allow the Kremlin to show the country and the world that Russia is a democracy and that there is no real opposition to President Vladimir Putin and his regime.

Like all conspiracy theories, this one suffers from one fatal flaw: there is no evidence whatsoever to support it. On the contrary, since Putin came to power in 2000, there hasn't been a single free and fair election at any level anywhere in the country. Why would the authorities begin now? More important, why would the Kremlin decide to sentence Navalny to five years and then release him the next day, which only raised his popularity?

It seems far more likely that the Kremlin had two plans. The harsher Plan A called for Navalny's arrest, but when the markets fell and protesters took to the street, they switched to Plan B and took a step back.

My personal observations on Manezh Square support this version. After I arrived just before 7 p.m., I was surprised by the fact that police presence was completely inadequate to the scale of the protest. There were no OMON troops and only two paddy wagons. The OMON arrived only around 8 p.m. From conversations with the OMON officers, I learned that they were called up at about 7:15 p.m. This is about when the prosecutor's office announced its request, which was first reported by Interfax at 7:45 p.m.

This wasn't all I learned from the demonstration on Tverskaya. The July 18 protest shattered the myth that the opposition doesn't have a broad base. The overwhelming majority of demonstrators were not political activists. They represented virtually every social stratum: students, yuppies, middle-aged white-collar workers, pensioners and even military veterans, who waved their military branch flag in front of the Duma.

I then tried to analyze the demographics of the protest by the passing cars that beeped their horns in support of the demonstration. After 15 minutes I gave up. All I got was an answer to the question: What kinds of cars do Muscovites drive? Everyone beeped, from rusting Russian Ladas to garish BMWs. The chorus of honking was even joined by a gold-colored Hummer that looked like it cost more than Arnold Schwarzenegger's entire Hummer fleet.

On Saturday morning, at the square in front of the Yaroslavsky Station, the cheering crowds greeted Navalny with the same joy that a previous generation met human rights activist Andrei Sakharov when he returned to Moscow from internal exile in 1986. It wasn't the end of the Communist Party's power, but it was the first harbinger of its downfall.

Victor Davidoff is a Moscow-based writer and journalist who follows the Russian blogosphere in his biweekly column..