During the debates leading up to the 1983 pastoral letter of the bishops of the United States on nuclear weapons, “The Challenge of Peace,” the great churchman Archbishop Philip Hannan of New Orleans said that many of the bishops were uninformed. I paraphrase, because the archbishop himself used much more colorful language, honed by years of working with the 82nd Airborne Division during World War II.

On the cover of my book chronicling war events between 1942 and 1943, Principalities and Powers, there is a photograph of armed soldiers at Mass in the ruined Cologne Cathedral, and I am pretty sure that the priest bowing at the altar is Father Hannan, since he was chaplain in charge of the cathedral for the occupying American troops. Apropos what principles the Church should follow with regard to military aggression, Hannan disagreed with the more nuanced Cardinal Bernardin, who was then the chairman of the National Council of Catholic Bishops Ad Hoc Committee on War and Peace. Hannan pointed out that he was the only bishop among the lot actually to have been in combat. The protocols of the NCCB letter did not become a template for the defense policies of President Reagan.

Much of what I presented in Principalities and Powers is more than amply corroborated by a new book by an authority on espionage, Mark Riebling, called Church of Spies: The Pope’s Secret War Against Hitler. In compelling detail, Riebling looks not only at the strategies that various anti-Nazi officers and other co-conspirators pursued to kill Hitler, but the kind of government structures that would need to be imposed on shattered Germany if the conspiratorial plots succeeded. Pope Pius XII was a central figure in the planning of these scenarios, as were the Dominicans and Jesuits in his network, precisely because of their ability to act independently of the bishops, some of whom were suspect or timid. In his 1988 book, Britain and the Vatican During the Second World War, Owen Chadwick cited testimony from the British representative to the Holy See, D’Arcy Osborne, who confirmed the Pope’s involvement in the June 20 plot, “Operation Valkyrie.”

Riebling’s book fleshes out more evidence showing how Pius XII worked secretly with his close confidant, Father Robert Leiber, SJ, who was in regular communication with Dr. Josef Müller, a German Catholic lawyer whose brazenness intimidated even Himmler. To collude with the pope, Müller took advantage of the cover given him by the Nazis to spy on Italians through Vatican officials. Leiber also conspired with a counter-spy, the chief of the Abwehr, German military intelligence, Admiral William Canaris.

The pope, operating under the code name “The Chief,” actually pioneered wiretapping, by having rooms in the Apostolic Palace bugged with a prototype of a tape machine (a wire was used) engineered by Marconi. Here he received Nazi officials and other unsuspecting diplomats. One of the earliest espionage successes was the pope’s warning of the invasion of Belgium. While Britain and the United States might have kept their distance from any involvement in any explicit assassination plot, Pope Pius was in correspondence with Neville Chamberlain and Lord Halifax before Churchill came on the scene, and Chamberlain indicated that Britain “would be willing to discuss any conditions asked for if convinced that business is meant.”

Hitler had an uncanny ability to survive assassination attempts: those who saw in him an incarnation of evil might call it a diabolic gift. Müller was another lucky survivor, even after the Nazis discovered some of his assassination plans in a letter with a Vatican letterhead. After the war, he was one of the founders of the Christian Democratic Union. Meanwhile, the pope also conspired against Mussolini, whose arrest so infuriated Hitler that he threatened to kidnap the pope and possibly take him to Lichtenstein: “I’ll go right into the Vatican… For one thing, the entire diplomatic corps are in there… We’ll get that bunch of swine out of there… Later we can make apologies.” According to the SS commander in Germany, Karl Wolff, the plan was thwarted only by the Allied liberation of Italy.

Two issues emerge here. First, Riebling’s compelling new evidence should put to rest the propaganda charging that Pius XII was at best a weak reed and at worst a Nazi sympathizer, or “Hitler’s Pope,” as he was dubbed by the revisionist historian John Cornwell, who made this Soviet propaganda the basis for his best-selling attack on Pius XII. Cornwell and other polemicists might find it hard to surrender ideology to fact in this as in so many other instances, but Riebling, following other historians who have exposed the falsehoods of this propaganda, including David Dalin and Rudolph Morsey, mounts a fairly irrefutable case in defense of Pius XII.

Secondly, there is the ethical question of tyrannicide, since the pope wanted Hitler killed. It cannot be said that Hitler was tyrannus in titular, which means a usurper, since he was elected to office, albeit by questionable means and intimidation. In the light of Thomism, usurpation would justify execution by a legitimate authority (In II Sent. D. XLIV, Q.ii,a.2). However, even in such a case, the right of an individual to take on the role of assassin is controverted, even though it is possible to argue that there could be a moral mandate for an individual to act thus when there is no possibility of public action, provided that he is a belligerent opposing an aggressor.

Prudence, of course, dismisses individuals acting from personal ambition and derangement: there can be no moral warrant for a Brutus or a Booth. Sic semper tyrannis is acid on the lips of demagogues, though one lends a sympathetic ear to fellows like Chaerea and his cohorts pouncing on Caligula. In 1415, the Council of Constance condemned the arrogation of assassination by an individual for the promotion of justice. The same Society of Jesus that lent conspirators to the plot to kill Hitler condemned tyrannicide in 1610, but that was in the case of an attack on a non-belligerent.

Even though Protestants such as Luther and Melanchthon approved tyrannicide, and John Knox wantonly invoked it to justify the death of Queen Mary, few anti-Nazi Protestant leaders during the Nazi period joined Catholics like Eugene Bolz, Alfred Delp SJ, and Claus von Stauffenberg. Without recourse to the Scholastic system, they regarded assassination as un-Scriptural. An honorable exception was Bonhoeffer, who visited the Vatican (where some plottings took place in the crypt of Saint Peter’s during the excavation of the apostle’s tomb) and admired clerical celibacy for the freedom it gave men to act against tyrants without fear of retaliation against wives and children. In his “Ethics,” Bonhoeffer quoted Aquinas in justification of tyrannicide, along with the examples of Ehud (Judges 3:15-30) and Jehu (2 Kings 9: 22-35). The close friend of Pius XII, Bishop von Preysing cited similar sources to justify the attempts on Hitler’s life.

In recent years, the policy of Pope Pius XII to avoid explicit mention of the Nazis and the Holocaust has been explained as a pragmatic, though futile, strategy to avoid retaliation against the innocent, such as happened in Holland after the pope spoke out, and, before that, when Benedict XV condemned the Armenian genocide by the Turks. The latest archival research, such as that conducted by Riebling using German and Vatican documents, shows that another factor was at work: at the behest of Müller and other conspirators, the pope maintained an outward reticence to make it easier for spies and counter-spies to confuse Nazi intelligence.

Fast forward, and the question now is how would humane people react today in similar circumstances? The relative passivity of people in the West in the face of genocide of Christians by Muslims in the Middle East and elsewhere is neither edifying nor encouraging. As for espionage, when representatives of Live Action, and the Center for Medical Progress more recently, filmed undercover interviews with Planned Parenthood functionaries, there were academics, even pro-life ones, who called these “sting operations” unethical for lying about the investigators’ identities. What would they say about Pius XII and his undercover agents? For that matter, what would those who absolutely oppose capital punishment with no mitigating circumstances say about the urgent appeal of Pius XII to hang those found guilty at Nuremburg?

When a systematic moral calculus rooted in natural law gives way to the vagaries of sentiment, the antinomianism that results often becomes enmeshed in its own contradictions. For example, recently the Catholic bishops of the state of Florida petitioned the governor to commute from execution to a life sentence a man who had murdered his wife, daughter, mother-in-law and sister-in-law. But Pope Francis had already denounced life-long imprisonment as “a hidden death sentence.” In such matters, the paternal counsel of a churchman like Archbishop Hannan would be helpful. The paratrooper surely would say, with his typical courteousness and anointed charity, that an ivory tower is no fortress in the battle against real evil.