Through association with a significant number of trade unions in Spain, the Spanish Regional Federation quickly grew to become one of the largest national chapters of the IWA with upwards of 29,000 members by 1873.

[3] The Glorious Revolution of 1868 overthrew the Bourbon Queen Isabella II and initiated the Sexenio Democrático period of Spanish history where liberal and radical theories were spread openly for the first time in decades.

The Barcelona Workers' Congress held in June 1870 provided the first opportunity for representatives from the emerging Spanish working class to organize publicly.

Eighty-nine delegates attended the Barcelona Congress where attendees voted to join the International Workingmen's Association which had been founded six years earlier in London with the aim of uniting workers and trade unions globally.

[4]: 168–169   Delegates at the Barcelona Congress were not united in how best to achieve the IWA's class struggle aims, and the newly formed FRE-AIT developed factions along the lines of Bakuninist collectivist anarchism, syndicalism, and cooperativism.

[4]: 173   After the fall of the Paris Commune, many communards fled to Spain as refugees which further stoked liberal and conservative fears of a socialist working class uprising.

While many factions of the FRE-AIT were weary of participating in electoralism, the organization welcomed Spain's transition to republicanism and campaigned heavily for workers' rights in the lead-up to the May 1873 general election.

[5]: 201   After left-leaning Francesc Pi i Margall's electoral victory, the FRE-AIT organized demonstrations in Barcelona and other cities to demand improved workers' rights and a more decentralized federal state.