Spain (PCE) and the Unified Socialist Party of Catalonia (PSUC) followed the official doctrine of the Soviet Union and supported the separate handling of war and revolution and defending the Second Spanish Republic. The PCE was the major communist party in the country, but the PSUC was the main communist organization in Catalonia. At the other extreme, the anti-authoritarian Workers' Party of Marxist Unification (POUM) of former Right and Left Opposition radically opposed Joseph Stalin and supported carrying out the revolution while the war was raging; the anarchists agreed on that point with the POUM. Tension was rising because chain of events that took place during the winter, heated the political climate and paved the way for what would take place later. The PCE's campaign against the POUM had begun in March during a political conference in Valencia. The POUM leaders were vilified and accused of being covert Nazi agents under a false revolutionary propaganda of being enemy agents infiltrated in the country. The POUM had come to propose an invitation for Leon Trotsky to reside in Catalonia, despite its differences with him. The POUM leaders were becoming increasingly wary during the spring of 1937. Tension in the streets of Barcelona was becoming evident of the arrival of a hot spring: the uncontrollable Patrullas de Control were led by José Asens and continued arbitrarily arresting murdering in their infamous paseos. Other anarchist patrols practiced expropriations. Josep Tarradellas, as Companys' right hand, was determined to unify the security forces in Catalonia under one command and to finish with the Patrullas de Control. On 26 March, Tarradellas banned members of the police from having political affiliation and demanded for all political organizations to hand over their weapons. Thus, anarchists withdrew from the government of the Generalitat of Catalonia. The open crisis forced Companys to give in to their demands, anarchists retained their weapons, and the Control Patrols remained in place. On 25 April, a force of Carabineros forced patrols of CNT in Puigcerdà to hand over control of the customs house. Juan Negrín, the Finance Minister, had resolved to end the anomaly under which the CNT controlled that important border. Puigcerdá had become a center of espionage, falsification of passports and clandestine leakage. Its mayor, Antonio Martin, insisted on general collectivization but raised his own livestock. After a violent confrontation occurred, he and several of his men were killed. Negrín then found