At first glance, this question sounds more like another Nazi conspiracy theory than a legitimate historical question (especially given the fact that it is not supported by any witness statements – let alone documentary evidence).
However, in reality it is actually a very natural question, because Reinhard Heydrich and other top Nazis that implemented the Final Solution (Holocaust/Shoah) were very concerned about possible reaction of the Christian Churches (Catholic and Protestants).
These churches have already forced the Nazis to shut down one mass murder project – the Aktion T4 involuntary euthanasia program which was terminated on August 24th, 1941 – right around the time Nazis made a final decision to exterminate all European Jews in gas chambers of specifically constructed for this purpose death camps – Treblinka, Belzec, Sobibor, Chelmno and in the extermination sections of Auschwitz and Majdanek labor camps.
Although the Holy See no longer had a “classic” intelligence service, its vast network of priests, monks, nuns and lay workers made it one of the most knowledgeable governments in the world.
Consequently, it was safe for the Nazis to assume that the Pope will be informed of mass murders of Jews (which were to be carried out in 100% Catholic nation highly loyal to the Vatican) in no time.
It was also safe for them to assume that the Pope who in 1937 has already issued (in German) the essentially anti-Nazi encyclical “Mit Brennender Sorge” (“With Deepest Concern”) would publicly condemn in the strongest words possible such an enormous crime against humanity and do everything possible (and seemingly impossible) to stop it right then and there.
And given the fact that after the Anschluss of 100%-Catholic Austria about 40% of Nazi Germany population was Catholic, he definitely had the power to achieve that objective.
Which was something that the top Nazis obsessed with the (totally delusional) idea of the “existential war with the Jewish race” simply could not afford. Consequently, they had to prevent the Pope from stopping the Holocaust – whatever it took.
Assassination of Pius XII was obviously out of the question as it would have very possibly led to (1) a religious civil war in Germany; (2) an immediate breakup with Italy and all Catholic allies of Germany (Hungary, Slovakia, Croatia, etc.); and (3) instant alienation of important neutral nations (Spain & Portugal). In addition, there was no guarantee that the next Pope would not be even more belligerent on this issue than Pius XII.
Consequently, the only way to prevent the Pope from declaring an open war on the Holocaust was to persuade him to keep silent – regardless of the information he would undoubtedly get from his sources in Poland. This was a very difficult job that required a highly skilled negotiator (manipulator, actually).
SS-Obergruppenfuhrer Reinhard Tristan Eugen Heydrich was the ideal man for the job. First, as the head of Reich Main Security Office (RSHA) he was the third most powerful man in the Third Reich (after Hitler and Himmler) and thus someone who would be taken very seriously by the Pope.
Second, he was, indeed, a highly skilled negotiator and manipulator (which are usually one and the same thing). Third, although he was baptized Catholic (on the insistence of his Catholic mother), his father was Protestant so he could maintain a “religious independence” from the powerful Pope.
Third, he knew everything about the Final Solution, because he was its Chief Architect. And, finally, he was just about the only one who could get to Rome in secret.
Heydrich was an experienced aircraft pilot. By that time, he has just return from his (final) tour on the Easter front where he (in the rank of a Luftwaffe major) flew the venerable Bf-109E single-seat fighter. Prior to that (during the invasion of Norway in 1940), he flew a heavy two-seater Bf-110 fighter.
Distance between Berlin and Rome is 1,200km. Bf-110 fighter has a maximum range of 2,410km – enough for a round-trip flight without refueling (even without external fuel tank). At that time, Luftwaffe aircraft were already based in Italy (they fought together in the Mediterranean) so a solo Bf-110 would not have attracted much attention on an airfield in Rome.
Mass shootings of the Jews in Ponary (Paneriai) – a modern-day suburb of Vilnius, the capital of 100% Catholic Lithuania, began in the beginning of July of 1941 (and obviously were almost immediately reported to the Vatican). The decision to build three dedicated (and top secret) extermination camps in Catholic Poland – Belzec, Sobibor and Treblinka – was made by top Nazis (Himmler and Heydrich) sometime in mid-October of 1941.
Hence, the meeting between Heydrich and Pius XII was most likely brokered by Cesare Orsenigo – then Apostolic Nuncio to Germany (successor to Eugenio Pacelli – future Pope Pius XII) and probably took place sometime in late September of 1941.
Archbishop Orsenigo was exactly the right man to broker such a meeting – he was a committed Fascist who was “frankly jubilant” when Hitler was appointed the Chancellor of Germany and urged German Catholic bishops to support the Nazi regime. In short, he was a pro-German, pro-Nazi, anti-Semitic fascist who felt right at home in Nazi Germany.
Judging from the undeniable fact that Pope Pius XII never publicly acknowledged (let alone condemned) the Holocaust (of which he was well aware), Heydrich mission was a total success.
How did he manage to convince the Pope to keep silent about the Holocaust? First, given the “standard operating procedures” of the RSHA chief, he employed a good old-fashioned blackmail.
At that time, Nazi Germany was the only country that was seriously investigating and prosecuting sexual abuse of minors by Catholic priests. Prior to these investigations (conducted by Gestapo headed by no other than Heydrich), pedophile priests were untouchable by the civilian prosecution – Catholic Church was simply way too powerful.
Power corrupts, so at that time the problem of sexual abuse of minors by pedophile priests was much worse than in the 2000s when the infamous global scandal finally broke out.
In his speech on May 28th, 1937, Dr. Joseph Goebbels – then Reich Minister of Public Enlightenment and Propaganda (this time more of the former than of the latter), confidently stated:
“There are cases of sexual abuse that come to light every day against a large number of members of the Catholic clergy. Unfortunately it’s not a matter of individual cases, but a collective moral crisis that perhaps the cultural history of humanity has never before known with such a frightening and disconcerting dimension.
Numerous priests and religious have confessed. There’s no doubt that the thousands of cases which have come to the attention of the justice system represent only a small fraction of the true total, given that many molesters have been covered and hidden by the hierarchy.”
Sounds like today’s article in a secular newspaper. Guess something in the Holy Roman Catholic Church has not changed in 60+ years.
Three hundred and twenty-five priests and religious were arrested by the Gestapo and charged with sexual abuse of minors. Twenty-one were found guilty by the Nazi courts while most of the others were sent to concentration camps without trial.
Given what we know today about the pedophilia among catholic priests, it was probably only the tip of the iceberg. For political reasons, Gestapo decided to persecute only a small number of child abusers, using all others as a powerful leverage against the Church (to make it keep silent and cooperate with Nazis).
Archbishop of Münster Clemens August von Galen was one of the few German catholic bishops who had a zero-tolerance policy against child molesters in his archdiocese so he was immune to the Nazi blackmail (which allowed him to become the leader of the anti-T4 resistance with impunity).
Pope Pius XII was obviously not. So when Heydrich presented him with comprehensive information about the magnitude of pedophilia problem in the Church in Germany, he was so shocked that he preferred to keep quiet about everything and anything to prevent this highly damaging knowledge from becoming public.
This and other information that would have seriously hurt the Church if become public – about homosexuality, sexual promiscuity, embezzlement and other financial and other crimes committed by priest, Church officials, religious and lay servants of the Church.
Information gathered in Germany and other countries (including Italy) by the gestapo and SD – the intelligence arm of the RSHA created by Heydrich in 1932.
Second, Heydrich probably used blackmail of a very different kind. A much, much more powerful blackmail. His Holiness was obviously aware that Josef Stalin has already annihilated the Catholic Church in the USSR and was well on his way to annihilating it in Lithuania and Eastern Poland territories acquired in 1939-40.
And that Nazi Germany was the only power capable of preventing the “Red Emperor” from annihilating the Church in the whole of Poland, Germany, Italy, the whole Western and Eastern Europe and in the whole world.
Heydrich informed the Pope that any public acknowledgement of the Holocaust (although Heydrich most likely used the euphemism “actions against the Jews”) could have led to the conflict between Wehrmacht and the Nazi regime that could have led to the defeat of Germany on the Eastern front and the subsequent conquest of Europe by the Bolshevist hordes – with predictable catastrophic results for the Church.
Finally, SS Obergruppenfuhrer most likely used the personal highly unpleasant experiences of Eugenio Pacelli in Bavaria, where the latter was the Apostolic Nuncio during the days of the infamous Bavarian Soviet Republic (established and run by Jewish politicians that had strong ties to Jewish and other Bolshevik leaders in Moscow).
These negative experiences – and the long list of Communists and other revolutionaries of Jewish blood (strengthened by then deep anti-Semitism in the Holy Roman Catholic Church) – helped Heydrich to convince the Pope that the existential threat of Bolshevism (to both Nazism and the Catholic Church) was the result of the global Jewish conspiracy and that to save the both from annihilation, Nazis simply had to undertake radical anti-Jewish measures.
In other words, that Nazis and the Church were in the same boat as allies – not adversaries.