Von Papen, papal chamberlain and Nazi negotiator
Franz Baron von Papen negotiated the concordat on behalf of Germany, even though he ahd been awarded the honourary title of papal chamberlain by Pius X in 1923. He faithfully served both Hitler and tthe pope, but escaped punishment at Nuremberg because his crimes were political.
Pius XII's Papal Chamberlains of the Sword and Cape wore the elegant black costume of the Spanish court, with white neck ruff and golden chain. Now called “gentlemen of His Holiness”, they are still appointed for the lifetime of the pope and form part of his entourage for one week a year, during the elaborate pontifical ceremonies. A papal chamberlain can be seen in a procession with Pius XII, at the bottom of the picture. The pope generally picked a nobleman to attend him and the influential German politician, Franz Baron von Papen, proved to be a brilliant choice.
Hitler had this former German Chancellor — and papal chamberlain — negotiate the 1933 concordat on behalf of Germany, with the papal nuncio, Cardinal Pacelli. On the eve of war, when von Papen's dual roles became a bit of an embarrassment, Pacelli, who had meanwhile become pope, let the appointment lapse.
Von Papen was tried for Nazi war crimes at Nuremburg, but escaped punishment because the court was not empowered to deal with “offences against political morality”  However, it examined Von Papen's role in Hitler's rise to power and established the following:
♦ “As ex-Reich Chancellor and prominent political leader, von Papen used his personal influence to promote the accession of the Nazis to power.” (p. 916)
♦ “As Vice-Chancellor, von Papen used his position and personal influence to facilitate the consolidation of Nazi control over Germany.” (p. 924)♦ “As Germany's most famous Catholic layman and as negotiator of the Vatican concordat, von Papen used his position and personal influence to participate in the consolidation of Nazi control over Germany and in Nazi preparation for aggression.” (p. 931)
♦ “Having achieved initial successes in consolidating Catholic support within Germany, von Papen undertook international consolidation of Nazi-Church relationships by negotiation of a Concordat with the Vatican.” (pp. 934-35) 
That von Papen should escape punishment on a technicality was too much for the Soviet member of the Tribunal whose country had suffered so grievously from the war and he protested, even though it could only be symbolic.
Von Papen faithfully served Hitler up to the very end aiding the Nazi plans of aggression both with his ability and his diplomatic skill. It therefore follows that defendant von Papen bears considerable responsibility for the crimes of the Hitlerite regime. For these reasons I cannot consent to the acquittal of defendant von Papen. 
After that the Vatican waited until 1959 when von Papen’s career was sufficiently forgotten. Then it gave him back his ostrich-feather fan and the honour of attending the pope.
1. Judgement : von Papen, Judgment of the International Military Tribunal for the Trial of German Major War Criminals, Nuremberg, 30th September and 1st October, 1946. http://avalon.law.yale.edu/imt/judpapen.asp
2. Individual Responsibility Of Defendants: Franz Von Papen, Chief Counsel for Prosecution of Axis Criminality, , International Military Tribunal, Nuremberg, Nazi Conspiracy & Aggression Office of United States Chief of Counsel for Prosecution of Axis Criminality ,Volume II, Chapter XVI, Franz Von Papen, U.S. Government Printing Office, Washington,1946, pp. 915-56.
3. Dissenting opinion of the Soviet Member of the International Military Tribunal, Major General Jurisprudence I. T. Nikitchenko on the Judgment concerning defendants Schacht, von Papen, Fritzsche and Hess and the accused organisations Reichscabinet, General Staff, and OKW. II. The Unfounded Acquittal of defendant von Papen. http://avalon.law.yale.edu/imt/juddiss.asp#papen