Within minutes of the Catalonian parliament declaring independence from Spain yesterday, the government of Prime Minister Mariano Rajoy lowered the boom.

The Spanish senate passed a measure authorizing Rajoy to implement Article 155 of the constitution, which grants the prime minister "extraordinary powers" to revoke the autonomy of Catalonia.  Rajoy didn't waste any time.  He immediately sacked Catalonia's President Carles Puigdemont, fired his ministers, dismissed the Catalonian parliament, and put the region's police force under national control.  He ordered elections for December 21.

Also, Spain's top prosecutor indicated that he would file rebellion charges against leaders of the separatist movement, including the president.

The reaction of Puigdemont and other Catalan leaders was muted, with calls for calm.  But a big demonstration has been called for Sunday in Barcelona, and with national police in charge, it's feared that the protest will turn violent.

NBCNews:

"Spain is living through a sad day," Rajoy said. "We believe it is urgent to listen to Catalan citizens, to all of them, so that they can decide their future and nobody can act outside the law on their behalf."

As he spoke, thousands of independence supporters packed the Sant Jaume Square in front of the Catalan regional headquarters in Barcelona, their earlier joyful mood somewhat dampened by Rajoy's actions.

In a stunning show of defiance of Madrid, the Catalan parliament had voted in the afternoon to make a unilateral declaration of independence.

Despite the emotions and celebrations inside and outside the building, it was a futile gesture as shortly afterwards the Spanish Senate in Madrid approved the imposition of direct rule.

Several European countries, including France and Germany, and the United States also rejected the independence declaration and said they supported Rajoy's efforts to preserve Spain's unity.

Catalonia is alone.  Not only does the rest of Europe and the world support Rajoy, but a vast majority of Spanish citizens also back the actions of their prime minister.  The opposition socialists also supported the implementation of Article 155, giving Rajoy extraordinary leeway in his crackdown.

The move for Catalonian independence was a long time coming.  And despite indications that Puigdemont wanting to avoid a showdown, more radical elements in the separatist movement forced his hand.

Bloomberg's Leonid Bershidsky was in Catalonia, taking the region's political temperature:

These last couple of days, I've been in Barcelona trying to make sense of the complex game that's been playing out here and the motives underlying it. For most of the day on Thursday, Catalan First Minister Carles Puigdemont appeared likely to backtrack on independence and call a regional election within the Spanish constitution instead. When reports of this came in, Antonio Banos, a leader of the most pro-independence party represented in parliament, the far-left CUP, changed the picture on his Twitter profile to an upside-down photo of Puigdemont, accusing the first minister of treachery. Pro-independence students started to gather by the government building to protest. Puigdemont's speech was pushed back and finally canceled. Banos turned the photo on its side. Finally, the first minister made an announcement: He was not calling an election after all. Instead, called on parliament to decide whether or not to declare independence. Banos turned Puigdemont's picture the right way up.

Puigdemont's dithering was actually an attempt to avert Rajoy's next move -- Article 155 of the Spanish Constitution, which allows Madrid to impose direct rule on a region. Rajoy's government refused to back off: It let Puigdemont know an early election wouldn't change its plans to remove his government. Puigdemont ended the day with nothing to lose. As he left the decision to parliament, in which his electoral bloc and CUP together hold a majority, he knew it would pass the independence declaration; he chose to go down fighting.

This is how history is made.  With no good choices, Puigdemont succumbed to the mob and backed independence.

What that mob does going forward will decide the fate not only of Catalonia, but of Rajoy as well.  While he has vast support for the crackdown, how he handles the implementation of Article 155 will make a huge difference in whether he keeps that support.  How will he remove Puigdemont and his ministers?  He could arrest them, but that would make martyrs of them and may inspire the crowds to violence.  What orders will he give the national police in dealing with demonstrators?  Will he seize local media outlets?  Will he allow his prosecutor to charge separatists with what amounts to treason?

A violent backlash will almost certainly unleash the socialist opposition, who may see a political opening if the streets of Barcelona and other Catalan cities run red with blood.  But Rajoy's course is set, and he has no choice but to grit his teeth and see the matter through to the end.