, 1720 Pope
Clement XI (Altieri) had been watching Polignac's career. On 17 May 1706 he showed his favor by naming Polignac an Auditor of the Rota (one of the Church's highest courts), a post made vacant by the promotion of Msgr. Joseph-Emmanuel de la Trémoille to the cardinalate. He spent the next three years in Rome. In 1712, he was created a
Cardinal Deacon by Pope Clement XI (Altieri) on 18 May 1712 but the nomination was made
in pectore, that is, his appointment was not made public at the time; it was only announced on 30 January 1713. At the time Polignac was a negotiator residing in a Protestant country, and it was deemed inadvisable to disrupt the course of events or cause offense by making his elevation public. While in Holland, he met and conversed with the famous Protestant philosophe,
Pierre Bayle, who had begun publishing the Dictionnaire in 1697. Once the Peace was concluded, he was presented with the red biretta at Versailles by Louis XIV on 6 June 1713. He did not go to Rome for the induction ceremonies, and thus had no deaconry assigned to him for many years. He did not attend the Conclave of April–May 1721, which elected
Innocent XIII (de' Conti), having been forbidden to travel to Rome by the French Regent, Philippe d' Orleans. But he was present at the Conclave of 1724, though he made a very late appearance on 23 April, after the Conclave had been in progress for seven weeks. He was eligible to participate, since he had finally been ordained deacon and priest, on 8 and 19 September 1722, by Msgr. Pierre Sabatier, the
Bishop of Amiens. After the Conclave, on 27 September, the new Pope named him Cardinal Deacon of S. Maria in Porticu. Polignac immediately wrote an account of the Conclave and sent it off to the new First Minister of
Louis XV,
Louis Henri, Duke of Bourbon. The Duke was so highly impressed by the report, both in content and style, that he had the King name Polignac French
Chargé d'affaires to the
Holy See, a post he held until 1732. He was thus absent from France for eight years. On 20 November
Benedict XIII (Orsini) promoted him to being
Cardinal Priest of S. Maria in Via. On 19 December 1725 he transferred to the title of S. Maria degli Angeli. These promotions were conditioned, to be sure, by his appointment as Chargé d'affaires. Also in 1724, Polignac was elected a member of the Roman Arcadian Academy, founded in 1692 in memory of Queen
Christina of Sweden; his academy name was Teodosso Cesisio. In 1730 he was in Rome and participated in the four-month-long Conclave which elected
Clement XII (Corsini). He did not, at the age of 78, travel to Rome for the Conclave of 1740. ==His position in French society==