At the start of November 1936 the rebel armies approached Madrid . The government of the Second Spanish Republic under Francisco Largo Caballero had done nothing to prepare the capital 's defenses for fear of alarming the population . José Cazorla was made alternate for Public Order under Santiago Carrillo in the Madrid Defense Council established on 7 November 1936 . Both Cazorla and Carrillo joined the Spanish Communist Party ( '' Partido Comunista Español '' , PCE ) in November 1936 . On 11 November 1936 over a thousand Nationalist prisoners were taken from the Model Prison and killed in the Jarama valley by the Republican 5th regiment as potential " Fifth Columnists " . The incident is known as the Paracuellos massacres . According to Antony Beevor the order for the massacre came from either Cazorla , as Carrillo 's deputy , or from the Soviet adviser Mikhail Koltsov . Hugh Thomas wrote that Segundo Serrano Poncela , the delegate of public order , was probably responsible , not Carillo , but Koltsov may have been involved
Paracuellos massacres
Paracuellos massacres
José Cazorla Maure