“Signor Mortara, I am sorry to inform you that you are the victim of a betrayal.” The officer felt uneasy, but he had his orders. “Your son Edgardo has been baptised, and I have been ordered to take him with me.”

The date was Thursday 24 June 1858, and the place was the Italian city of Bologna. At that time, Bologna lay within the Papal States – the swathes of northern and central Italy that were ruled directly by the pope as an earthly monarch. A squad of the papal police force had come to take 6-year-old Edgardo Mortara from his Jewish parents, Momolo and Marianna, and deliver him to the church authorities in Rome.

A terrible scene ensued. The police insisted that they were only following the orders of the local Inquisitor, Fr Pier Gaetano Feletti. The Inquisitor himself insisted that he was acting under instructions from the Vatican. In the face of the pleas of Edgardo’s family, Fr Feletti agreed to a 24 hour reprieve, albeit with reluctance. He was worried that the Jewish family would murder their child in order to prevent him from being brought up as a Christian.

When the 24 hours were up, Edgardo was taken by carriage to Rome and placed in the House of Catechumens, an institution in which Jewish and Muslim converts were instructed in the teachings of Catholicism. On the journey to Rome, according to one version of the story, Edgardo showed a marked interest in the doctrines of the Catholic faith and an eagerness to go to church. His police guard later suggested that this was the result of childish curiosity and the attention bestowed on him by his Catholic fellow passengers.

This cruel situation had come about because Edgardo had been secretly baptised. Shorn of its ceremonial accompaniments, baptism is a very simple rite: one sprinkles the person with water while saying “I baptise you in the name of the Father and of the Son and of the Holy Spirit”. And that’s it. Anyone can do it, even if they are not a Christian. (See, for example, this prayer book from 1925: at the beginning are printed brief instructions for the emergency baptism of a dying person.) In Edgardo’s time, as today, church law provided that a baby could be baptised only with the parents’ consent and by a clergyman using the approved Catholic ceremonies; but those requirements could be disregarded if the child was in danger of death. In any event, whether it is conferred lawfully or unlawfully, a baptism that fulfils the minimal requirements just mentioned is valid and irreversible. That was what did for the Mortaras. A Jewish child who had been baptised was regarded by the church as a Christian, and he could not be raised by unbelieving parents who would try to turn him away from his new faith.

Edgardo’s case was not unique. There were several other instances of Jewish children who were abducted by the papal government to be raised as Christians – usually because a Catholic servant of the family had performed an illicit baptism. Some Jewish families had adopted the practice of requiring servants to make a notarised statement on leaving employment declaring that they had not baptised any of the family’s children.

These inhuman incidents were able to happen because they took place within the personal realms of the pope. The Papal States dated back to the middle ages, but by the nineteenth century they were an extraordinary anachronism, a relic of an older theocratic age. Since the time of the French Revolution, the Italian peninsula had been swept by waves of invasions and revolts, inspired by the new ideas of liberalism, nationalism and constitutional government. The tide of history was running against the notion that the pope had the right to rule over a worldly kingdom through the medium of religious law enforced by civil police. The Papal States were politically unstable, as well as economically backward; but the papacy had decided to try to cling on to power through police repression and censorship. Opera lovers will recognise this as the world of Tosca. Dissidents were persecuted, Protestants were discriminated against, and Jews were confined to ghettos. The pontifical government was living on borrowed time, propped up by French and Austrian troops, and funded by loans from – oh, the irony! – the Rothschild banking dynasty. Yet the Catholic hierarchy continued to behave as if it was still the Counter-Reformation.

Embedded in the reactionary Catholicism of the times was a noxious vein of antisemitism. Jews had lived in Italy since before the time of Christ, but in the Papal States they had long been subject both to popular hostility and to legal repression. They were, for example, forced to wear badges identifying their status, and they were required to listen to compulsory sermons aimed at converting them. It was technically illegal for more prosperous Jewish families like the Mortaras to employ Catholic servants; such arrangements inverted the rightful hierarchy of Christians over Jews. In more recent times, the harshness of the anti-Jewish laws had been relaxed somewhat – Pope Pius IX (1846-1878) prided himself on his benevolence in this regard – but Jews were still second-class citizens at best. This was an age of rampant antisemitism: for example, it was still seriously believed that Jews kidnapped Christian children and consumed their blood (the notorious blood libel).

Nonetheless, the Mortaras and their supporters in the Jewish community did not take Edgardo’s abduction lying down. They fired off letters – respectfully worded, of course – to Fr Feletti, the pontifical Secretary of State, and Pope Pius IX himself. The abduction of Edgardo was always morally dubious even within the framework of traditional Catholic theology. Catholicism is a highly patriarchal religion. It could be – and was – argued that Momolo Mortara’s authority as father over his son Edgardo was sacrosanct and could not be overridden even by the pontiff. But such arguments went nowhere; Pius IX did not appreciate being schooled on moral theology by Jews.

The international press became interested. Editors used the plight of the boy from Bologna to fortify their readers’ pro- or anti-Catholic sentiments. The French ambassador got involved, as did the Rothschilds and the legendary Anglo-Jewish philanthropist Sir Moses Montefiore. The Jewish community of Rome, whose officials were at the forefront of the Mortaras’ efforts, viewed these interventions with some concern, believing from their own long experience that the Jews of the Papal States could only lose from any attempt to strongarm the pope.

Accounts of how Edgardo behaved in the House of Catechumens and how he conducted himself during meetings with his parents differed dramatically, along predictable lines. The official version, in which he gloried in his new Christian life, looks very much like propaganda. The natural assumption is that a 6-year-old boy forcibly separated from his parents must have been devastated by the experience, and that his parents’ testimony to that effect must have been true and correct. On the other hand, Edgardo does seem to have adapted himself to his new situation, and doubts developed among some of the Mortaras’ allies about where his loyalties lay. After leaving the Catechumens, Edgardo seems to have settled quite well into his new life with the other boys at a church school in Rome, and in due course he was ordained as a Catholic priest.

Who had baptised Edgardo? Suspicion soon fell on Anna Morisi, a former servant of the Mortaras, and it duly turned out that she was the guilty party. Her story was that she had administered the baptism during a life-threatening illness which Edgardo had suffered in infancy. A local grocer had suggested that she baptise the child to ensure that he went to Heaven, and she had taken this advice. Several years later, she had told another servant in the neighbourhood what she had done, and it was shortly after that that the Inquisitor had got wind of what had happened. Another of Morisi’s employers recalled independently that she had talked about baptising Jewish babies several years previously, at a time when one of the Mortara children was seriously ill.

This version of events did not go uncontested. The witness evidence was conflicting, and it appears that Morisi had been trying to get a dowry from the local priests; this may have given her a financial interest in suddenly coming out with her story several years after the event. The Mortaras went to some lengths to prove that Morisi was no simple, God-fearing young girl. Marianna said that she had been a liar, and other witnesses claimed that she had been involved in theft. Predictably, given the times, her love life was held up as evidence of bad character. Bologna was garrisoned by Austrian troops, and Morisi appears to have had a liking for handsome young men in uniform. Leaving such matters aside, it is probable on balance that Morisi did baptise Edgardo, no doubt oblivious to the havoc that her act would cause in the future.

The Mortara affair was one of the rude shocks that awoke the upper echelons of the Catholic Church to the realities of the modern world. They may have been able to get away with this sort of thing in the middle ages, but the game had changed. The affair arguably even altered the course of European history, since it may have influenced Emperor Napoleon III of France to allow the Kingdom of Piedmont to annexe most of the Papal States in 1859-60, an important step in the creation of the modern Italian nation.

Extraordinarily, some ultra-conservative Catholics today still defend the papacy’s actions. But there is no way of regarding the abduction of Edgardo as anything other than viciously antisemitic. The church’s argument was that a Catholic boy could not be allowed to be brought up by non-Catholic parents and diverted from the true path – but this argument does not pass muster even on strictly Catholic principles. As every priest at the time knew, there were uncountable thousands of baptised children in Italy who were being brought up by parents who had turned away from the church or had never really adhered to it in the first place. Yet their families were never broken up by the papal police. That treatment was reserved for Jews.

When Piedmontese troops freed Bologna from papal control in 1860, Fr Feletti was arrested and put on trial by the new government. Even within the framework of the old laws, it was argued, he was guilty and deserving of punishment: he provided no proof that he had followed correct procedures in ordering Edgardo’s seizure, and he appeared not to have ascertained properly that the baptism had been validly performed. The court found these arguments unpersuasive and acquitted him.

Fr Feletti was small fry, though. At the centre of the controversy were Pope Pius IX and his chief minister, Cardinal Giacomo Antonelli. There is a longstanding tendency to see Pius as a kindly old buffoon who was manipulated by Antonelli. Antonelli himself was a devious politician who became a cardinal without ever being ordained a priest, and he was said to be more interested in money and women than in religion. There may be an element of truth in these caricatures, but Pius was no innocent dupe. He took a close personal interest in Edgardo’s upbringing, and he strenuously resisted attempts to induce him to release the boy. He was an affable man of personal piety and virtue; but he was also wilful and intransigent. He cared not what governments, ambassadors or journalists (“the truly powerful people of our times”) had to say on the matter. He did not have the slightest qualm of conscience in keeping Edgardo separated from his parents, because he knew with unshakeable certainty that God was on his side. Sometimes the worst popes are the holy ones.

Not that Pius was lacking in defenders. Catholic writers and newspapers praised his stoutheartedness and applauded his actions. The pope, they said, had acted in accordance with his religious duties; and besides, the boy was clearly loving it. His parents might be upset to have lost him, but they had lots of other children, and in any case they should have thought of that before they broke the law by employing a Catholic servant. What was more, they could immediately be reunited with Edgardo by becoming Catholics themselves, in which case they would also be granted eternal salvation. These lines of argument are oddly echoed by no less a person than the professional atheist Richard Dawkins. In The God Delusion, Dawkins uses the Mortara case as part of his ludicrous argument that ascribing parents’ religion to their children amounts to child abuse. He seems to think that the Mortaras were culpable because they had employed a Catholic servant due to silly Jewish scruples about working on Shabbat, and because they refused to make a fake conversion to Catholicism to get their son back (“Couldn’t they cross their fingers, or whisper ‘not’ under their breath while being baptized?”).

In the meantime, events were moving on. Edgardo wrote to his parents on a number of occasions; but he couldn’t resist trying to convert them to Catholicism, which led to a breakdown in communications. In 1864, a similar case to Edgardo’s, involving a Roman Jewish boy named Giuseppe Coen, reportedly influenced Napoleon III to temporarily withdraw his troops from what remained of the pope’s territories. In 1870, the French troops left for the last time to fight the Franco-Prussian War, and the Italian army entered Rome. The pope’s earthly power was extinguished, and the papacy enjoyed an extended toys-out-of-pram moment until finally the small plot of land known as Vatican City was handed back to Pope Pius XI in 1929. When the Eternal City fell to the Italians, Edgardo was visited by his brother Riccardo, a soldier in the invading army. Edgardo, now a young man of 19, insisted that Riccardo remove his “murderer’s uniform” before he would speak to him. He then slipped out of Rome and fled to Austria before his parents could catch up with him. Coen’s parents were similarly disappointed when they were reunited with a petulant teenager who wanted nothing more to do with them.

It seems that Momolo never recovered from his son’s abduction. In 1871, another servant of the family died under mysterious circumstances, and Momolo was initially convicted of her murder amid allegations that he had become an angry and violent man. The verdict was subsequently reversed by a higher court, and he died shortly afterwards. Marianna made her peace with Edgardo and died in 1890. As we have noted, Edgardo himself became a priest. A clever man, he learnt several languages and became a missionary preacher. He eventually wound up in Belgium, where he died on 11 March 1940, just before the Nazi invasion. It was a mercifully timed demise. The baptism that had taken him from his parents and made him an international celebrity would have cut no ice with the SS.