Hundreds of thousands of Catalans are expected to fill the streets of Barcelona on Tuesday for the Spanish region’s first commemorative day since its leader declared independence last year and pitched the country into constitutional crisis.

Supporters of splitting the wealthy northeastern region from the rest of Spain have in recent years used the September 11 “Diada,” the anniversary of the fall of their coastal capital to Spanish forces in 1714, to promote the cause.

This year, Catalonia’s leader Quim Torra, who took over from his exiled predecessor after Madrid ended an unprecedented period of direct rule, has called for a mass rally in support of his bid for a binding referendum on independence.

“Our government has committed to making the republic a reality,” Torra said in a televised address to mark the occasion. “I wish you all a very good Diada. Long live free Catalonia.”

He wore a yellow ribbon signifying support for nine politicians whose jailing for their role in the independence bid is one of the Catalan government’s biggest grievances.

Socialist Prime Minister Pedro Sanchez, who took power in June, has taken a softer approach to one of the thorniest issues in national politics than that of his conservative predecessor Mariano Rajoy, but he has stood firm against allowing a vote on secession, or any unilateral attempt by Catalonia to secede.

Last year’s Diada, in which marchers often climb on each other’s shoulders in shows of the traditional sport of forming human towers, fell as the regional government was preparing to hold a referendum in defiance of Madrid, which ultimately sent riot police to try to stop the vote.

Torra’s predecessor and ally Carles Puigdemont then declared independence, prompting Madrid to impose direct rule on the grounds that Barcelona had violated the 1978 constitution which states that the country is indivisible.

Extra police will be deployed during the anniversaries of events in the independence bid. The government’s regional delegate, asked last week about 600 agents being sent as reinforcements, said this was the normal approach to scheduled rallies.

Divisions over the question of secession are stark in Catalonia, which makes up around one fifth of Spain’s economic output and already has a high level of autonomy in areas including education and health, and its own police force.

A poll by the Centro d’Estudis d’Opinio in July showed 46.7 percent of Catalans surveyed saying they wanted an independent state, just ahead of 44.9 percent who did not.

Last year’s banned referendum delivered a majority vote for independence, but turnout was low.

A pro-secession coalition regained control of the regional parliament at a regional election in December that Rajoy had hoped would put paid to the independence bid, but a staunchly pro-union party emerged as the single biggest winner.