Pro-union supporters rallied two days after the Catalan government was sacked

Huge numbers of people poured onto the streets of Barcelona.

At the moment the battlefield in the constitutional war for the heart and soul of Catalonia is being fought through peaceful protest.

For both sides, flags are the most potent symbols; carried, sharp as spears, in the campaign for political supremacy. The number of people demonstrating is significant - as it has been when the separatists have taken to the streets.

The pro-unity organisers claim more than a million. That will be no doubt contested but it was certainly in the hundreds of thousands.

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Image: So far, the battle for Catalonia's future has been peaceful

Whilst the Catalan separatists accuse the central government of staging a coup - by suspending the region's autonomy and outlawing the freely elected government - the unity supporters say they're the majority but their voice has been drowned out by a noisy and better organised independence movement.

History has become a tool for both and this clash is about the past as much as it is about the future.

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It is interesting - in a country where the rule of the dictator Francisco Franco is still remembered first hand - that some people in both groups freely use the word fascist to describe the other.

For Madrid, Sunday's demonstration will be used as a mandate; it will draw strength from the bobbing heads in the sea of red and yellow and hope that what at the moment is a gradual approach to end the rebellion will work.

It is a gamble though.

As a tactic, it is shrewd. A massive crackdown in this region of 7.5 million people would play into the hands of the separatist movement and severely damage Spain's credentials as a modern democracy.

Image: Organisers claim a million people joined an anti-independence march in Barcelona

But as a strategy, much could go wrong. If the disputed leader, Carles Puigdemont, and others are arrested, would the snap election called for 21 December be fair?

Opponents of Madrid would say the poll had been conducted in a climate of intimidation.

It may be that the elections are allowed to run their course and everyone is allowed to campaign.

This is where the big bet comes in; Spain's PM will be praying that the remain camp wins the day. On the other hand what happens if the separatists are the victors?

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The underlying problems, of course, will remain.

No one gets to choose their history; the constitutional crisis, and its underlying roots in centuries of tradition, is not going to disappear.

The only way to deal with this crisis in the long term will be through smart political dialogue and a recognition of Catalonia's unique history.