Inquisition: The Reign Of Fear, by Toby Green

Founded in 1478, the Spanish Inquisition was for 300 years the most notorious institution in the world. There had been a Papal Inquisition since the end of the 12th century, initially to extirpate the Albigensian heres. But the Spanish variant, ostensibly aimed at heresy, was primarily a political vessel to allow the "Catholic kings" Ferdinand and Isabella to impose a monolithic hegemony in Spain.

Their motives were to weaken localism and strengthen central power as well as to profiteer, but they did genuinely fear a fifth column, which was why the Inquisition initially targeted the conversos (Jews who had converted to Christianity) and moriscos (Muslims who had likewise abjured their faith, after Ferdinand and Isabella expelled the Moors). The Spanish Inquisition was under the aegis of the king of Spain, although the appointment of the Inquisitor-General had to be approved by the Pope.

In reality, Spain could always twist the Vatican's arm. Sixtus IV was pressurised into allowing a Spanish Inquisition by the threat from Ferdinand and Isabella that othwerwise they would not support the Papacy in its war against the Turks. Its excesses were always because of political pressures, not because it was an arm of the Counter-Reformation. Beginning with the conversos and moriscos (absurdly believed to be in alliance with Turkey, Islam or Calvinism) the Spanish Inquisition swept into its net freemasons, Hindus, Muslims, Lutherans, Huguenots, alumbrados (a mystical sect), bigamists, fornicating priests, homosexuals, drug takers, "witches" and freethinkers.

The first Inquisitor-General, Tomas de Torquemada, sacked the papal inquisitors and set up his own office in 1478. Three years later, at the first grand council (auto-da-fé), he condemned six men to burning at the stake, even though they were not guilty according to the rules of the old Papal Inquisition. Probably the heyday of the Inquisition in Spain was 1480-1550, although it remained powerful thereafter.

Soon its tentacles spread around the world, first to Portugal, the Canaries and Cape Verde, then to Goa, Mexico, Peru, Colombia and Brazil. With the full panoply of a proper court, the Inquisition handed down a variety of punishments besides execution. Culprits could be fined, exiled or sentenced to the galleys. The ultimate penalty was "relaxing" – a wonderful euphemism for burning at the stake. If the victim repented, he was garrotted first. But it was torture that made the Inquisition a byword for infamy. Victims would be racked, given the water torture or suspended from the ceiling by a pulley with weights tied to ankles, combined with lifts and drops to dislocate limbs.

In contrast to those, like Henry Kamen, who have tried to rehabilitate or "normalise" the Spanish Inquisition, Toby Green is full of Swiftian savage indignation about its excesses. His scholarship is thorough and careful and he has made good use of the work of giants in the field such as Gustav Henningsen and Jaime Contreras.

He is particularly good at the many scams and rackets. Entirely self-financing from the sale of property confiscated from heretics, the Inquisition targeted rich victims on trumped-up charges. Sexual predators on its staff accused the husbands and sons of attractive women, thus getting the wife or mother to offer herself to have charges dropped.

When the Inquisition investigated you, it would send you a bill for the cost of its researches. But the pervasive corruption was not enough to lose credibility. Freethinking and the Enlightenment sounded the death-knell. When anti-Jesuits like Pombal came to power in Portugal, the Inquisition was on the ropes. Still a powerful force in Lisbon in 1750, it was a busted flush by 1774. In Spain it limped on to denounce the French Revolution, but was then finished off by Napoleon.

Critics of Green would no doubt say that the excesses of the Inquisition have been exaggerated. It is true that out of 150,000 cases in more than 300 years, only 3-5000 ended in execution. And if the censorship of books by the Inquisition was so powerful, how come it utterly failed to put a dent in Spain's golden age of literature?

But Green is on firm ground when he likens the mindset of Inquisitors to the McCarthyite witchunters of the 1950s and suggests that Franco and Salazar were in many respects the Inquisition reborn. Franco preached redemption through suffering, while the McCarthyite obsession about reds under the bed mirrored the Inquisition's fantasies about an "enemy within". The Inquisition represented deep fear and paranoia about "the Other". In an excellent quasi-Freudian summing-up, Green points to neurosis, repression and a distorted view of sexuality as key factors in the mental world of inquisitors. Alas, their descendants are still with us and at work in Guantanamo Bay.

Frank McLynn's new book, 'Warriors', will be published by BBC Books in October

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