Why did the Spanish Civil War start in July 1936?

On the night of 17 July 1936, the Spanish army, inspired most of all by General Franco, started the Spanish Civil War by rebelling against the Second Republic. A central goal of the rebels was the destruction of left-wing organisations. Franco’s fellow officer, General Queipo de Llano, instructed his subordinates on how to treat the ‘Bolshevik’ activist with this chilling sentence: ‘I authorise you to kill him like a dog and you will be free of all responsibility’. Attitudes such as this made the war a terrible tragedy: before its end, in April 1939, 325,000 had died in battle and from disease. Historians estimate that Francoists executed at least 150,000 during and after the war. Victory for the Francoist side brought economic and political isolation for Spain until the 1950s and the denial of basic rights until the late 1970s. Only in recent years have relatives of the executed started to learn where their loved ones are buried.