In 1937 there were nine intelligence and counter-intelligence organizations with their own networks of agents in the Republican held zone: the communist held DEDIDE , the SIEP , the army’s secret service, the Carabineros’ secret service, the foreign ministry’s, the Generalitat’s, etc. Even, the International Brigades had its own intelligence service run by the soviet NKVD. This organizations held prisoners in its own secret prisons, named "Checas" after the Cheka Soviet organization. Owing to the confusion and often arbitrary arrests, the Republican minister of Defense, Indalecio Prieto decided to reorganize the intelligence services in order to increase the control of the central government.
Establishment of the SIM
On August 9, 1937, Prieto decided to create a new secret service, the Servicio de Información Militar or SIM, merging all the intelligence services inside the Republican zone. The main goals of the SIM were to combat the Nationalist’s intelligence service, the SIPM , to neutralize the Fifth Column and to restrict the activity of the "uncontrollables". Nevertheless, it was also used by the PCE, to persecute its political enemies. It had 6,000 agents only in Madrid and a budget of 22 million pesetas. It was organized into six military sections and five civilian sections. The SIM aided to stop the atrocities of the "uncontrollables" and destroyed many networks of the Fifth Column. In 1938, the SIM uncovered the clandestine Falange in Catalonia, detaining 3,500 persons. Nevertheless, the SIM had a deserved bad reputation among the population. It had clandestine prisons in Madrid and Barcelona, used torture to obtain confessions and carried out extrajudicial executions of suspects. Moreover, in February 1938military tribunals were established which worked under summary procedure and without any legal guarantees for the accused. According to Gabriel Jackson, the SIM carried out around 1,000 executions. In March 1939, the head of the SIM in Madrid supported the Casado’s coup. With the end of the war the SIM was disbanded.
