The massacre at Portella della Ginestra, coming just a few days after an unexpected victory for the left in Sicily's first ever regional elections, claimed 11 dead and 55 wounded. It was a remarkably low casualty toll given the narrowness of the pass where they were gathered and the appalling wounds inflicted by bullets ricocheting off the rocks.
As intended, though, it shocked the Sicilian peasantry back into the arms of the establishment, an establishment in which the interests of the big landowners, the Christian Democrats, the Church and the Mafia all converged with the full approval and even encouragement of the US government.
The exact chain of responsibility for the massacre has never been established, although it almost certainly won the tacit approval of all the big power- brokers and attracted no more than a murmur of disquiet from the Christian Democrats' notoriously repressive Interior Minister Mario Scelba. The man who organised the attack, the charismatic bandit Salvatore Giuliano, was no more than a tool of the larger forces but he nevertheless enjoyed their protection for a long time afterwards.
While ceaseless attempts were theoretically being made to capture Giuliano, he was in fact holding court to a never-ending stream of journalists and admirers at his home town of Montelepre just over the hills from Portella della Ginestra. "The only people unable to find Giuliano were the police," a court sentence concluded years later, by which time Giuliano had been betrayed and killed, and the pax mafiosa in Sicily had become so normal it had lost much of its power to shock public opinion.
The Mafia thus re-established itself as a bulwark against Communism. It remained on intimate, if occasionally ambivalent, terms with the Christian Democrats throughout the Cold War as Italy's political system became increasingly bogged down and Cosa Nostra built up a vast international empire in drugs smuggling and other rackets.
Some of the lessons of Portella della Ginestra are still valid today, notably that the fortunes of any mafia crime organisation - whether in Sicily, Calabria, Naples, northern Italy or elsewhere - depend largely on the complicity, or at least the weakness, of the state structure with which it must compete for control of territory.
Of course, the big change has been the end of the Cold War. In Italy's case it occurred not so much in 1989 as in 1992, when the Christian Democrat- led order collapsed under an intolerable burden of corruption scandals and the Mafia, taking advantage of the political chaos, launched a full- scale war on the establishment. It was in 1992 that Giovanni Falcone, the magistrate who did more than anyone before or since to penetrate the secrets of Cosa Nostra and dismantle its leadership, was blown up along with his wife and police escort on the way into Palermo from the airport. Within two months, Falcone's closest colleague Paolo Borsellino was also eliminated in a massive car bomb that exploded outside his house.
The result of these murders, the most shocking of a long string of so- called cadaveri eccellenti or "illustrious corpses", was to galvanise popular opinion, the politicians, the police, the magistrature and horrified members of Cosa Nostra itself into an unprecedented counter-attack on the Mafia. Over the next three years, with the help of new legislation and a witness protection programme, hundreds of new informers came forward and one high-profile arrest after another was made, particularly in the upper echelons of the Corleonesi, the clan that ran Cosa Nostra in the 1980s and early 90s and was responsible for its strategy of terror against the state.
Trials for the murders of Falcone and Borsellino were put together in record time, based on the kind of detailed evidence of which most prosecutors can usually only dream.
Meanwhile, all sorts of dirty linen started coming out. It led, most spectacularly, to the arrest and trial of Giulio Andreotti, the grand old man of the Christian Democrat party, on charges of mafia collusion and murder. But there were also precious new insights into such mysteries as the kidnapping and murder of Aldo Moro, the Christian Democrat leader, in 1978 and the death of Roberto Calvi, the banker with connections in both the Mafia and the Vatican, in London in 1982.
Then something happened. Part of it was no doubt a loss of momentum - these things have always gone in waves - but mostly it was due to an attempted political counter-revolution bent on rolling back the extraordinary achievements of the judges. When Silvio Berlusconi, a man himself under investigation for gross malpractice in his media empire, became prime minister in 1994, he all but stopped the magistrates dead in their tracks and the work of the parliamentary anti-Mafia commission ground to a near standstill.
Mr Berlusconi's downfall at the end of 1994 was followed by a year and half of political stagnation, and then the arrival of the present centre- left government led by Romano Prodi. Despite the presence of several prominent anti-Mafia campaigners in the ruling coalition, however, yet more ground is being lost. Why?
Partly it is because of the weakness of the Prodi government, which relies on a fringe left-wing party to make up its majority in parliament and has concentrated its limited strength on getting Italy into the single currency. Partly it is because of a calculated risk taken in the name of lasting constitutional reform. An extraordinary cross-party commission is currently examining changes to the electoral system, the balance of power between the president, the government and parliament, and also the judicial system.
The problem is that in order to get Mr Berlusconi to agree to a decent electoral system, he is being effectively bought off with judicial reforms that risk unravelling much of the anti-Mafia magistrates' good work. Instead of helping the magistrates by bolstering their presence in crime-ridden cities like Reggio Calabria and increasing the efficiency of the appallingly slow Italian court system, the emphasis is all on reining-in the judges and subjecting them to greater legislative and political control.
The Mafia is taking full advantage of the signals emanating from Rome, and Sicily in particular has slumped back into a state of despondency. The positive results of the mid-1990s are still being felt, notably in Calabria where a slew of recent arrests has weakened some of the most powerful groups operating their world-wide rackets from there.
But the risk, as the magistrates closest to the coal face can attest, is that life is going to get a lot worse again very quickly. "The Mafia is beginning to build up resistance to the tools we have devised to combat its influence," said the Palermo prosecutor Antonio Ingroia. "If we do not update our weapons then the next round will be lost."