His investment in terror imbued the collective Spanish psyche with a determination never again to undergo such civil conflict or to suffer another dictatorship.
That remains the case to this day, exactly 40 years after his death.
However, unlike Hitler's Germany or Mussolini's Italy, where external defeat led to denazification processes, there was no equivalent in Spain - and the shadow of his regime still bedevils politics.
Franco's vengeful triumphalism had been fostered in the military academies, where officer cadets were trained to regard democracy as signifying disorder and regional separatism.
As the dictatorship was rapidly dismantled, some of its senior military defenders did not share the massive political consensus in favour of democratisation and so endeavoured to turn back the clock at several moments in the late 1970s and, most dramatically, in the attempted coup of Colonel Antonio Tejero on 23 February 1981.
After the defeat of the coup in 1981, the attitudes of the armed forces were changed by Spain's entry into Nato in 1982, which shifted their focus outwards from their previous obsession with the internal enemy.
Scarred by the horrors of the civil war and the post-war repression, during the transition to democracy Spaniards rejected both political violence and Franco's idea that, by right of conquest, one half of the country could rule over the other.
However, what was impossible in a democracy was a counter-brainwashing.
Moreover, especially in his later years, Franco did not rule by repression alone: he enjoyed a considerable popular support. There were those who, for reasons of wealth, religious belief or ideological commitment, actively sympathised with his military rebels during the civil war.
Then, from the late 1950s onwards, there was the support of those who were simply grateful for rising living standards.
Although in the many national, regional and municipal elections that have been held in Spain since 1977, openly Francoist parties have never gained more than 2% of the vote, a residual acceptance of the values of the Franco dictatorship can be found in the ruling conservative Popular Party and its electorate.
Accordingly, no government has ever declared the Franco regime to be illegitimate. It was not until 2007 that the Law of Historical Memory made tentative efforts to recognise the sufferings of the victims of Francoism.
Equally slow has been the process of removing the symbols of the dictatorship, the Falangist equivalent of the swastika - its emblem of the yoke and arrows - on church walls, street names commemorating Franco's generals and, above all, the huge basilica and towering cross of the Valley of the Fallen where the dictator is buried.
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Today, along with the still open wounds of the civil war and the repression, two other shadows of the dictatorship hang over Spain - corruption and regional division. The Caudillo's rigid centralism and its brutal application to the Basque Country and Catalonia had left more powerful nationalist movements there than had ever existed before 1936.
The democratic constitution of 1978 enshrined rights of regional autonomy for Catalonia and the Basque Country with which the right has never been comfortable.
Mass pressure in Catalonia for increased autonomy met with an intransigence that has fuelled a campaign for independence.
Drawing on a residual Francoist centralism, the Popular Party has fomented hostility to Catalonia in particular for electoral gain. The consequent divisiveness, at times bordering on mutual hatred, is one of the most damaging legacies of Francoism.
The other is the corruption that permeates all levels of Spanish politics. Needless to say, there was corruption before Franco and corruption is not confined to Spain. Nevertheless, it is true that the Caudillo used corruption both to reward and control his collaborators.
Recent research has uncovered proof of how he used his power to enrich himself and his family.  In general, the idea that public service exists for private benefit is one of the principal legacies of his regime.
It will thus be many years before Spain is free of Franco's legacy.
Paul Preston is Professor of Contemporary Spanish Studies at the London School of Economics and leading writer on Franco. Among his books are Franco: A Biography and The Spanish Holocaust
Spain's Gen Francisco Franco fought a brutal war against democracy with the aid of Hitler and Mussolini and thereafter presided over a regime of state terror and national brainwashing through the controlled media and the state education system.