Today we observe the memorial of Translation of Relics of St. Vincent de Paul. “Translation” is a bit of jargon from our French roots. It refers to the the solemn transfer (or “translation”) of the relics of Saint Vincent to their new home in the chapel of the mother house in Paris. For more history visit the Vincentian Encyclopedia.
For history buffs this article recounts the events that was described as one of the great public religious events of the decade.
See also the Encyclopedia entry describing the intrigue required to preserve the relics and the role of the  Daughters of Charity in hiding and safeguarding the relics.
At the time of the French Revolution, Father Sicardi  managed to hide the relics from the pillagers of Saint Lazare by remaining in the Sisters’ mother house the whole day of 13 July 1789.

The Encyclopedia article continues…

heart of VincentHe returned to Saint Lazare from the Sisters when it was safe to begin to pick up the pieces. Since it was increasingly clear that the Congregation would be suppressed or at least moved from Saint Lazare, he joined Cayla and his fellow assistants in gradually preparing the remaining treasures of the Congregation for safekeeping. The relic of the heart of Saint Vincent was put in his charge sometime in 1790. He seems also to have been given the responsibility of guarding the Founder’s clothing as well as his personal items (breviary, walking stick and the like), a valuable painting of the saint and a collection of his writings. Someone, possibly Sicardi, developed a method to hide the relic: hollowing out the pages of a large book, volume two of François Giry’s Vie des Saints. When it was closed, it was just one of a number of books and other objects and gave no hint of its contents. Among the personal items Sicardi took is a manuscript of meditations for the annual eight-day retreat at Saint Lazare, copied by Cyr-Jacques Renaudon (b. 1695) in 1720. Sicardi’s name appears on the title page of his important witness to the piety of pre-Revolutionary French Vincentians.

The plan developed to transfer these objects to the Vincentian house in Turin, which Sicardi knew well. He would be accompanied by two other Vincentians, Edward Ferris and Thomas-Félix Lebrun. Four Daughters of Charity would make up the rest of the traveling party, Sisters Colasson, Jolié, Lespinasse and Maltret, who wrote up an account of their adventures. This group of Sisters had been missioned to Hennebont but, when in 1791 they refused to take a prescribed oath, they left their house. According to Sister Maltret, “A cannon had been aimed at our door and the wick was lit” to force them out. After seeking refuge in other houses in Belle-Ile and Rennes, they arrived in Paris. Their new mission was to begin a house in Turin. The group of seven, all in lay clothing, left Paris 12 September 1792. Despite their secular dress, they were recognized one day in an inn and were in peril of their lives. Providentially, a general who had come to know the Vincentians during a retreat he made at Saint Lazare vouched for them and sent them safely on their way.

Once arrived in Turin, the letters and the clothing were recognized officially, and the heart relic was exposed in the Vincentian chapel there. On one occasion, 17 July 1793, the relic was brought about in procession through the city to pray for rain, which subsequently fell in torrents. When Sicardi left for three months, he entrusted the precious relic again to the Daughters of Charity in the city. The reliquary apparently tipped over on the Sisters’ altar, and small fragments of the heart fell out. The Sisters gathered them up into four little reliquaries which Sicardi allowed the Sisters to retain. When, in 1796, the Sisters were forced to leave Turin for Vienna ahead of Napoleon’s troops, they had seals put on their relics to authenticate them. In 1800, the Vincentian house in Turin was suppressed, so Sicardi, still responsible for the now-reduced relic, brought it to his family and then deposited it with his confrere Georges-François Bertholdi (or Bertoldo) (1742-1804). He died only two months later but, fortunately, he had deposited it for safekeeping with an acquaintance whose name has not been recorded, and Sicardi was then able to recover it from him.

In late 1804, Cardinal Fesch, archbishop of Lyons, learned of its existence probably while attending the coronation of his nephew, and he determined to ask for the heart for himself. In a few days, he decreed that the Turin Vincentians should hand it over to a French general, Jacques-François de Menou, sent to transfer it to France, along with the book in which it had been kept. The cardinal’s reasons were that he loved relics in the first place and that, since Paris had the body, so Lyons, where Vincent had been a pastor, should have his heart, before which Fesch would be able to pray.

The transfer was more difficult and less complete than the cardinal imagined. One issue was the ownership of the relic. The archbishop of Turin wrote to Fesch declaring, incorrectly, that it was the property of the Vincentian house in Turin, having been given to them, and not just placed there on deposit by permission of the superior general. This would have made the transfer to Fesch more difficult. The cardinal would not be convinced and insisted that Menou take possession as quickly as possible. The Turin Vincentians, however, had their own plans and secretly excised two heart valves which they placed in another reliquary and which remain in Turin.

The further diminished relic and reliquary were replaced in the book that had brought them to Turin, and arrived in Paris in May 1805, where they were authenticated in the presence of Brunet and Sister Deschaux, who had seen the heart exposed in Saint Lazare. Then the three items were brought to Lyons about 1 August 1805, and a solemn festival was organized on 29 September to welcome them to the cathedral where the reliquary was enshrined. The Daughters of Charity of Lyons received the large book, which is now kept at the rue du Bac in Paris. In 1814, when Hanon left prison, he tried to get the relic back. He queried Sicardi about it, and the latter explained that Cayla had left the heart with him not as a gift but as a deposit to be returned to the superior general once the Congregation had been restored in France. Hanon then went to Lyons with this document and talked with the vicar general, but its return was deemed impossible. Although a subsequent archbishop of Lyons eventually returned the heart to the Daughters of Charity, he placed the original reliquary in the diocesan museum, where it remains.