The creation in July 1936 of the Unified Socialist Party of Catalonia, born from the merger of a part of the Catalan socialists with a part of the Catalan communists, turned the relation of the Spanish Communists with the Third International in a unique and anomalous case with respect to the situation previously existing inside the communist movement. The presence, within the same State, of two political parties both proclaiming themselves legitimate representatives of the Communist International (the Spanish Communist Party and the new Catalan organization) challenged the dogma "one State, one party" established by the Moscow-led international organism since its very foundation in 1919. The formal adhesion of the Catalan "section" was made public only in the summer of 1939, well after the end of the civil war and with the majority of both the leaders and the militants already in exile. Drawing on unpublished papers held in Spanish and Russian archives (RGASPI), the A. goes over the entire tortuous course of the confrontation, at times extremely harsh, involving the two different communist parties, the International with its leading organs and the two wings the Catalan party itself soon ended up to break into.
Keywords: Spanish Communist Party (PSE), Unified Socialist Party of Catalonia (PSUC), Third International, Catalan nationalism, Spanish exile, RGASPI