According to the summary in Wikipedia - "The Reichskonkordat ("Concordat between the Holy See and the German Reich") is a treaty negotiated between the Vatican and the emergent Nazi Germany. It was signed on 20 July 1933 by Cardinal Secretary of State (and later Pope Pius XII) Eugenio Pacelli on behalf of Pope Pius XI and Vice Chancellor Franz von Papen on behalf of President Paul von Hindenburg and the German government. It was ratified September 10, 1933 and it has been in force from that date right up until the current day. [My emphasis].The treaty guarantees the rights of the Roman Catholic Church in Germany. When bishops take office Article 16 states they're required to take an oath of loyalty to the Governor or President of the German Reich established according to the constitution. The treaty also requires all clergy to abstain from working in and for political parties. Nazi breaches of the agreement began almost as soon as it had been signed and intensified afterwards leading to protest from the Church including in the 1937 Mit brennender Sorge encyclical of Pope Pius XI. The Nazis planned to eliminate the Church's influence by restricting its organizations to purely religious activities." [end of Wikipedia quote]
The 1933 Concordat has always been controversial among historians - for obvious and perfectly respectable reasons - but has also been used by anti-clerics to suggest that the future Pope Pius XII, Eugenio Pacelli who signed in his capacity as Secretary of State to Pius XI, was some kind of Nazi supporter (or "Hitler's Pope" as John Cornwell put it). What is almost invariably ignored in these discussions is that Achille Ratti (who became Pius XI in 1922) and Eugenio Pacelli who would succeed him as Pius XII in 1939, had been heavily involved in trying to negotiate a Concordat with the Soviet Union in the 1920s! In fact it was Pius XI's predecessor Pope Benedict XV, who employed Achille Ratti (then Papal Nuncio to Poland) to contact Lenin on behalf of persecuted Catholic and Orthodox clergy. ***
Like the Nazis in 1933, the newly created Soviet Union in the 1920s was trying to make itself respectable in the international community while at the same time, the Catholic Church was trying to protect the rights of Catholics in these newly minted totalitarian states. The Vatican's attempt to come to terms with the Soviet Union should be open to the same objections as its negotiations with the Nazi regime but in practice the former negotiations are almost invariably ignored. No doubt this is partly due to the failure of the negotiations with the Soviets, but is this really the main reason? Surely historians who express very negative views of the Reichskonkordat and impugn the motives of Pope Pius XI and his Secretary of State, should at least refer to their previous behaviour in relation to the Soviet Union; was THAT motivated by sympathy with Communist dictatorship.??
Again to quote Wikipedia (this time on the subject of Holy See - Soviet Union Relations )
"Worried by the persecution of Christians in the Soviet Union, Pius XI mandated Berlin nuncio Eugenio Pacelli to work secretly on diplomatic arrangements between the Vatican and the Soviet Union. Pacelli negotiated food shipments for Russia, and met with Soviet representatives including Foreign Minister Georgi Chicherin, who rejected any kind of religious education, the ordination of priests and bishops, but offered agreements without the points vital to the Vatican. Despite Vatican pessimism and a lack of visible progress, Pacelli continued the secret negotiations, until Pius XI ordered them to be discontinued in 1927, because they generated no results and were dangerous to the Church, if made public." ........
The article continues:
"Pius XI described the lack of reaction to the persecution of Christians in such countries as the Soviet Union, Mexico, Germany and Spain as a "conspiracy of silence". In, 1937 the Pope issued the encyclical Divini Redemptoris, which was a condemnation of Communism and the Soviet regime." He did name a French Jesuit to go to the USSR and consecrate in secret Roman Catholic bishops. It was a failure, as most of them ended up in gulags or were otherwise killed by the communist regime."
Note that 1937 was also the year in which Pius XI published his condemnation of Nazi ideology and practice in Mit brennender Sorge (With Burning Sorrow.) [A five-member commission drafted the latter encyclical. According to Paul O'Shea the carefully worded denunciation of aspects of Nazism was formulated between January 16–21, 1937, by Pius XI, Cardinal Secretary of State Eugenio Pacelli (later Pope Pius XII) and German cardinals Bertram, Faulhaber and Schulte, and Bishops von Preysing and von Galen.]
One of the few who does deal with the attempted Concordat with the Soviet Union is the British historian Michael Burleigh in his 2006 book Sacred Causes: Religion and Politics from the European Dictators to Al Qaeda. (see Chapter 3: "The Churches in the Age of Dictators.) Again I quoted from Burleigh's book in a discussion on the Politics.ie website in January 2012 (see under). In contrast to some of the other points I made, there was little or no reaction to this one; presumably this is because most people have no idea that the Vatican engaged in these negotiations!
Rory Connor
Updated 11 August 2016
*** As per the Wikipedia article Pope Benedict XV and Russia "During the winter of 1918–1919, some "twenty [Orthodox] bishops were murdered together with thousands of priests and religious". ... Several Orthodox bishops from Omsk and Simbirsk wrote an open letter to Pope Benedict XV, as the Father of all Christianity, describing the murder of priests, the destruction of their churches and other persecutions in their areas."
Politics.ie History Forum "Nazis, The Catholic Church and Sexual Abuse"
Kilbarry1 
Vatican Concordats
While I'm at it,
the following quotation from Burleigh's book concerns the attempts of two
future popes - Pius XI (Achille Ratti) and Pius XII (Eugenio Pacelli) to
negotiate a Concordat with the Soviet Union in the 1920s. It throws an interesting light on the frequent denunciations of
the Vatican concordat with Nazi Germany in 1933.
Vatican concordats with governments do not imply approval of the governments. Of course there is a danger that a vicious dictatorship will use the agreement in order to boost its international standing - and that is precisely what the Soviet government was trying to do in the early 1920s. Indeed negotiations with the Vatican broke down because several governments - including both Britain and fascist Italy(!) - recognised the Soviet Union in 1924 and the Soviets no longer needed an agreement with the Vatican. However the future Pope Pius XII continued to negotiate even "when the execution in Leningrad of a Polish Catholic priest complicated matters" !!
.... Both nuncios, Ratti in Warsaw and the younger Pacelli in Munich (until 1925, when he moved to Berlin as nuncio to the German Reich), were closely involved in Rome's diplomatic initiatives with the Soviets. The Vatican initially welcomed the fall of the Romanovs, believing that this would herald a new era of freedom and opportunity for the Roman Catholic Church in the debris of the Tsarist Empire. Benedict XV employed Ratti to contact Lenin on behalf of persecuted Catholic and Orthodox clergy.
In late 1921, the Vatican offered the Soviet Union humanitarian assistance hurriedly incorporating a broader secret agreement which, capitalising on the disarray of the Orthodox Church would - they imagined - have enhanced Roman Catholic activities in Russia. The aid was provided but the wider agreement remained a dead letter. Assisted by the German Government which saw relations with Russia as a means of terminating Germany's pariah status, the archbishop of Genoa held talks with the Soviet foreign affairs commisar Chicherin on board an Italian cruiser with a view to negotiating a concordat. A further series of meetings took place at Rapallo, based on Vatican calls for freedom of conscience and Soviet demands for diplomatic recognition. Effortlessly overcoming the extreme distaste for German (Jewish) Bolsheviks that he is alleged to have expressed in 1919, Pacelli met Maxim Litvinov, the Soviet Union's (Jewish) foreign minister, at the Berlin villa of the brother of the German ambassador to Moscow.
When Mussolini recognised the Soviet Union on 8 February 1924, and was quickly followed by, among others, Britain, Norway, Austria, Greece and Sweden, the Soviets ceased to regard negotiations with the Vatican as important except for the question of aid. Pacelli continued to negotiate with the Soviets in Berlin until mid-August 1925 when the execution in Leningrad of a Polish Catholic priest complicated matters. However he met Chicherin twice in 1925 and 1927, discovering that his Soviet interlocutors were prepared to concede less and less, and such talks abruptly stalled under Stalin, to whom the Vatican was an irrelevance.
From Sacred Causes by Michael Burleigh - Chapter 3 "The Churches in the Age of Dictators", section II - "The Vatican, Communism and Fascism" page 164
Vatican concordats with governments do not imply approval of the governments. Of course there is a danger that a vicious dictatorship will use the agreement in order to boost its international standing - and that is precisely what the Soviet government was trying to do in the early 1920s. Indeed negotiations with the Vatican broke down because several governments - including both Britain and fascist Italy(!) - recognised the Soviet Union in 1924 and the Soviets no longer needed an agreement with the Vatican. However the future Pope Pius XII continued to negotiate even "when the execution in Leningrad of a Polish Catholic priest complicated matters" !!
.... Both nuncios, Ratti in Warsaw and the younger Pacelli in Munich (until 1925, when he moved to Berlin as nuncio to the German Reich), were closely involved in Rome's diplomatic initiatives with the Soviets. The Vatican initially welcomed the fall of the Romanovs, believing that this would herald a new era of freedom and opportunity for the Roman Catholic Church in the debris of the Tsarist Empire. Benedict XV employed Ratti to contact Lenin on behalf of persecuted Catholic and Orthodox clergy.
In late 1921, the Vatican offered the Soviet Union humanitarian assistance hurriedly incorporating a broader secret agreement which, capitalising on the disarray of the Orthodox Church would - they imagined - have enhanced Roman Catholic activities in Russia. The aid was provided but the wider agreement remained a dead letter. Assisted by the German Government which saw relations with Russia as a means of terminating Germany's pariah status, the archbishop of Genoa held talks with the Soviet foreign affairs commisar Chicherin on board an Italian cruiser with a view to negotiating a concordat. A further series of meetings took place at Rapallo, based on Vatican calls for freedom of conscience and Soviet demands for diplomatic recognition. Effortlessly overcoming the extreme distaste for German (Jewish) Bolsheviks that he is alleged to have expressed in 1919, Pacelli met Maxim Litvinov, the Soviet Union's (Jewish) foreign minister, at the Berlin villa of the brother of the German ambassador to Moscow.
When Mussolini recognised the Soviet Union on 8 February 1924, and was quickly followed by, among others, Britain, Norway, Austria, Greece and Sweden, the Soviets ceased to regard negotiations with the Vatican as important except for the question of aid. Pacelli continued to negotiate with the Soviets in Berlin until mid-August 1925 when the execution in Leningrad of a Polish Catholic priest complicated matters. However he met Chicherin twice in 1925 and 1927, discovering that his Soviet interlocutors were prepared to concede less and less, and such talks abruptly stalled under Stalin, to whom the Vatican was an irrelevance.
From Sacred Causes by Michael Burleigh - Chapter 3 "The Churches in the Age of Dictators", section II - "The Vatican, Communism and Fascism" page 164
