Pacelli's belief that secret diplomacy was always preferable to other forms of activity, particularly public outspokenness, played into the hands of men like Adolf Hitler and Benito Mussolini. Pacelli was instrumental in negotiating a concordat with Germany, which Hitler never had the smallest intention of observing. Pacelli's tactic of private, indeed secret, remonstrance but public silence suited Hitler admirably. In the 1920s the Catholic Centre Party was strong and well-organised, especially in Bavaria. Its leader, Brüning, was the most effective of the Weimar politicians. It might have failed in any event to stop Hitler but Pacelli's policy made his task much easier, as Brüning's bitter comments testified. Not only did Hitler persecute any Catholic who stood up to him, and suppress Catholic newspapers — all without any opposition from the Vatican — but in July 1933 the demoralised Centre Party supplied the votes to give Hitler his two-thirds majority to pass the notorious Enabling Act, on which his dictatorship was essentially based. Eventually, with Pacelli's consent, the German Catholic bishops reversed their condemnation of Nazism, which had been their initial reaction to its odious programme. 

As Secretary of State Pacelli continued his policy of secret remonstrances and public silence. Pius XI, who as Achille Ratti had been a prominent mountaineer, used to taking risks and demonstrating his fearlessness, was anxious to denounce both the Axis dictators in unmistakable terms. Pacelli dissuaded him, at all stages, from saying  anything controversial. Thus the remilitarisation of the Rhineland, the attack on Ethiopia, including the use of poison gas, and the shocking invasion of Albania on Good Friday, all took place without a word of condemnation from the Pope. In due course, the horrors Hitler inflicted on overwhelmingly Catholic Poland, and his murder of nearly six million Jews, went without public rebuke from Rome. It is not true that Pacelli, as some of his critics argue, admired Hitler or supported his aims to the smallest degree. He hated them. It is true, on the other hand, that he did his feeble and limited best to protect the Roman Jews. But he never used the moral prestige of the Catholic Church to confront Hitler with his crimes in a dramatic and public manner. It might not have had any real effect. It might indeed have led to his seizure by Hitler and possible martyrdom. That would have made a remarkable climax to a life of service to the Church. As it was, Pius XII missed all the opportunities. As D'Arcy Osborne, the British diplomat attached to the Holy See, said succinctly, the papal policy could be summed up in two words, "anxious inactivity".

Oddly enough, after the war Pope Pius XII, who had marked it by his public taciturnity, became increasingly loquacious. Encyclicals, pronouncements, speeches and obiter dicta flowed from him in ever-growing volume, most of them on entirely non-political subjects. He delighted in receiving and talking to Hollywood stars, sportsmen, celebrities and visiting firemen to Rome (almost his last audience was given to Alec Guinness). This was the period, of course, when the conmen crept in too. Galieazzi-Lisi, the medical "expert" who attended him in his last illness, was permitted to embalm him by what he claimed was a marvellous process, preserving all the organs intact. As a result the pope's body went green and the papal guards protecting it complained of the smell of decomposition. There had earlier been rumours of the aged pope seeing miraculous visions, which this book says were well-founded. Thus Pius XII went to eternity in an atmosphere of eccentric religiosity verging on scandal. He was not the "Nazi pope", as some have asserted. But his papacy was inglorious, to put it mildly. And to promote his canonisation, on the present state of the evidence, would be most imprudent.