The Battle of Guadalajara in March 1937 was a defensive victory for the Republic against the Nationalist insurgency, in which the Italian Garibaldi Brigade made up of antifascist international volunteers distinguished itself against fascist conscript `volunteer' levies despatched by Mussolini to aid Franco. The neapolitan communist leader Giancarlo Pajetto had success with an armoured vehicle broadcasting propaganda calling on the fascist militiamen to surrender. The Garibaldi Brigade fought in the name of the slogan of the liberal socialist leader Nello Rosselli: Today in Spain, Tomorrow in Italy. Many of the Italian veterans of the Spanish Civil War did go on to be leaders of the Italian Resistence of 1943-5. Rosselli however was not among them. He was assassinated by fascist agents along with his brother in France before the outbreak of World War II, a tragedy fictionalised after the fall of Mussolini by Moravia in `The Conformist', and brought to the screen by Bertolucci in the film of the same name.
Map from Thomas `The Spanish Civil War' Penguin London 2003