He was involved in the foundation of the Partit Comunista Català in 1928 and it was here that he met his future wife Núria Folch i Pi.
However, Sales soon left the BOC, disillusioned with what he felt to be the party’s rigid discipline and its retreat from its Catalan roots.
With the outbreak of the Spanish Civil War, Sales enrolled in the Catalan Military Academy (Catalan: Escola de Guerra) and, as an officer, was sent first to the anarchist Durruti column[Notes 3] in Madrid and then to a militarised battalion on the Aragon front.
Following the defeat of the Spanish Republic at the hands of the fascists, he was one of the last to take the road to exile and cross into France at the Col d’Ares.
As a publisher, Sales founded Club Editor and was actively involved in keeping Catalan culture and literature alive during the Franco dictatorship.
Following his return from exile, he joined the Democratic Union of Catalonia (Catalan: Unió Democràtica de Catalunya).