Banning the separatist symbol of the independence movement goes beyond sports. Last week, the Spanish government banned the flag from being displayed at government buildings during national elections scheduled for June 26. After the announcement, Catalan officials invited citizens to fly the Estelada flag at their homes.

Spain is sensitive to the movement. In November, Catalan lawmakers voted to break away from Spain by 2017, an action that Spanish officials said they would block. As Time explains, secession of the region of 7.5 million people could have massive implications for all of Spain:

Catalonia is arguably Spain’s most powerful economic region, making up just 16% of the country’s population while providing a fifth of the country’s economy. Though Catalonia has roots as an independent state dating back to the 11th century, it has long been a part of Spain, while maintaining its own language, culture, cuisine, and semi-autonomous government.

Since the soccer club’s founding in 1899, FC Barcelona has been rooted in Catalan pride and the region’s desire for independence. During the 1910s in the early years of the club, Catalan was the team’s official language. In one match, in 1925, during the dictatorship of Miguel Primo de Rivera, fans responded to the Spanish national anthem with jeers and whistles. The government responded by shutting the stadium down for six months.

On April 6, 1936, troops under the command of Francisco Franco, who would later become the country’s fascist dictator for nearly 40 years, arrested Josep Sunyol, the club president and Catalan nationalist leader, just north of Madrid, and shot and killed him on the spot. The club views his death as one the most pivotal moments in its history.

In the late 1930s, in the midst of the Spanish Civil War, the government banned the display of the Estelada flag at games, and forced the club to remove the flag from its crest and change its official language from Catalan to Spanish. Faced with the threat of retribution from the government, some team members took refuge in South America.

Under his regime, Franco further politicized soccer in Spain, which the blog Outside of the Boot describes:

[Franco] adopted the capital’s biggest club, Real Madrid to make it a perfect personification of his fascist leadership. He shrewdly observed that by supporting Real Madrid, he would put the operations of FC Barcelona, a symbol of Catalonian pride and honour, out of articulation. Barca, in turn, would become the symbol of republican resistance, against Franco’s oppressive regime and its oppression of the Catalan culture.

That pressure was most apparent in 1943 during the semifinals of the Copa del Generalisimo, today called Copa del Rey, when Real Madrid beat Barcelona 11-1 in what is still considered a controversial match. According to The Guardian:

Then on the day of the match, to make sure Barça’s players got the centralist message, Spain’s director of state security visited their dressing room just before kick-off. Packing a loaded gun—though some Madridistas question the packed piece—he quietly reminded the visitors that “you are only playing because of the generosity of the regime that has forgiven you for your lack of patriotism.” A singular inspirational team talk having been delivered, the following kickabout was only ever going to end one way. Real scored early, then made it two on the half-hour, whereupon Barça, fearing lethal consequences, properly capitulated; it was 8-0 to Madrid by halftime. The second half was a relative non-event, the game ending 11-1.

The composition of the team today is far different from the FC Barcelona of that era. Soccer is a multibillion global sport, and the team is one of the sport’s richest. Most of its best players are now from Argentina, Brazil, Uruguay, and elsewhere, though a handful is Catalan. Having said that, among Barça fans, Madrid still represents the the oppression of the Franco years. The ban on the Estelada flag for Sunday’s Copa Del Ray final is likely just another example of that.