At no time has Satanism been so widely practised as in Paris in the 1670s. During this period Louis XIV – the Sun King, the builder of magnificent Versailles, the commander of the greatest army in Europe – was in his late thirties and at the height of his powers.

Yet, while he won for himself glory by personally conducting the victorious campaigns that greatly extended France’s borders, in his capital Black Masses were celebrated daily. Scores of beautiful women who made his Court the most splendid in Europe lay naked on altars and allowed often repulsive, elderly priests to copulate with them, then murder infants so that their blood might be offered up to the Devil.

The revelation of these appalling practices began in 1676 with the trial of the Marquise de Brinvilliers. This terrible woman and her lover first visited hospitals with gifts of food for the inmates, into which they had inserted a variety of poisons to try out their effects. She then murdered her father and two of her brothers, but an attempt on her husband failed. She fled but was caught, tried and condemned to be first tortured then executed. Before her death she declared, ‘If I cared to talk you would learn that half the aristocracy are as guilty of poisoning as I am.’

And she was right. Fathers, mothers, uncles and aunts were being suddenly taken ill and dying by the score; victims of a callous generation impatient to inherit their money.

The trial of the Marquise led to police enquiries which revealed that there were dozens of men and women in Paris growing rich as fortune tellers of every description. Under the guise of palmists, clairvoyants and casters of horoscopes they were selling not only amulets and love potions but also poisons.

When this was reported to the King – an adulterous but otherwise high-principled, religious man – he was horrified and ordered his Lieutenant of Police, La Reynie, to embody a special court, called the Chambre Ardente, to purge Paris remorselessly of these iniquitous criminals.

Among those arrested were Le Sarge and La Voisin, who had been partners but since quarrelled. Both, hoping for leniency by incriminating the other, gave the names in court of many ladies of high rank who had been their patrons. It then emerged that not only had these Duchesses and Marquises bought poisons with which to kill off unwanted husbands, they had also lent themselves to Black Masses to secure Satan’s aid in supplanting their rivals.

In many cases the object had been to win the love of the King. Numerous attempts had been made to bring about the death of the great love of his youth, the sweet-natured Louise de la Vallière. She had several times been suddenly stricken with acute illness, but survived. Henrietta, the witty, charming sister of our Charles II, and wife of King Louis’s brother, had died poisoned, it was believed, by the favourite sodomite of her husband, who was a homosexual. The King’s first love, Cardinal Mazarin’s niece, the Countess de Soissons, was accused but given time to fly the country. By that time dozens of the nobility, fearing for their lives, had fled into exile.

For the past ten years Athénaïs de Montespan, the most beautiful woman in France, had been the King’s reigning mistress and given him several children, whom he had actually adopted as members of the Royal Family. But her immense power was waning and she had already been physically supplanted by Mademoiselle de Fontanges. This lovely young blonde died before she was twenty.

At length, at one trial, de Montespan’s name was mentioned as a client of La Voisin. In great agitation La Reynie dashed with the news to the King. For her to become involved would have greatly damaged Louis’s dignity. He promptly ordered that any further mentions of her should be deleted from the court’s proceedings, but written down by the Chief of Police and this single copy brought to him. This was done and later burnt by the King. But La Reynie had kept his own notes. These survived and from them we have the whole awful story.

Between April 1679 and April 1682, the Chambre Ardente issued warrants for the arrest of three hundred and nineteen persons. Many fled the country in time but one hundred and four were sentenced, including La Voisin, to death by hanging and quartering or burning at the stake, or to the galleys for life or exile. After the court was closed the King dealt with a further hundred or so, sending them to remote prisons and convents or to penal settlements in America.

After La Voisin’s death her daughter revealed to the court that ten years earlier the Marquise de Montespan had submitted her body to a Black Mass with intent to supplant La Vallière as the King’s mistress: that ever since her success she daily had aphrodisiacs put into the King’s food or wine: that more recently, in the hope of retaining the King’s love, she had again spread herself on a Devil’s altar to be enjoyed by the hideous old Abbé Guibourg: that in La Voisin’s garden there was a chalet in which countless abortions and Black Masses had taken place, the latter performed by dozens of different priests.

Behind it was found a furnace in which the corpses of hundreds of infants – whose life-blood had gushed into chalices resting on the mons veneris of great ladies – had been burned.

And all this took place in the Sun King’s ‘good’ city of Paris during the years of his greatest glory.