Roberto Rossellini’s 1945 film is a blazingly urgent and painful bulletin from the frontline of Italy’s historical agony: the Axis power that had belatedly turned against the Mussolini fascists only to be humiliatingly occupied by Nazi Germany on whose orders the dictator was reinstalled in the northern Salò puppet state, resplendent in contemptible impotence and pathos, with Rome at its defeated and compromised centre. It was a film that used the so-recently-devastated real streets and people of Rome on location for a project on which Rossellini started script work well before the end of the war, building on ideas by...