an 1842 portrait of Cardinal Luigi Lambruschini (x). Today (May 12th, 2025) marks the 171st anniversary of his death.
In the 1830's the British government was on a crusade to suppress the African slave trade. […] By 1838 Lord Palmerston, the British foreign secretary, was growing impatient. Slaves were still being shipped by the thousands from Africa to Cuba and Brazil. Consequently, he looked to the United States and the Papacy for help. [...] Palmerston had more reason for optimism with regard to the Papacy. In 1815 Pope Pius VII had issued a brief condemning the slave trade in response to an appeal from the British foreign secretary, Lord Castlereagh. In July, 1839, Thomas Aubin, the British consul in Florence, wrote to the pope's secretary of state, Cardinal Luigi Lambruschini, asking for a declaration from the Holy See. Aubin noted that the British had been working for years to suppress the trade. While most European countries had willingly co-operated with them, the British had trouble with certain countries which were "in spiritual communion with the Holy See." Aubin was sure that a public declaration on this subject by the pope would be "most advantageous to the cause of humanity and would render a great honor to the Roman government."
When Gregory learned of Aubin's letter, he decided to put the matter before the cardinals who served in the Congregation for Extraordinary Ecclesiastical Affairs. […] To assist the other cardinals in their deliberations, Lambruschini drew up a lengthy memorandum on the subject. In his report, he sharply criticized the British government for its long record of hostility towards the Holy See. Considering these tensions, he declared that it would be neither "convenient" nor "useful" for the pope to make any allusion to the British if he were to issue a letter.
Lambrushini also noted that there were many defenders of slavery and the slave trade in the Church who could offer a host of reasons to justify them. Among other points, they would make reference to Abraham and Jacob and other patriarchs owning slaves; to St. Paul's counsel to slaves to obey their masters; and to the Council of Gangra (330) and other councils which appeared to affirm the legitimacy of slavery and the slave trade. None of these claims impressed him much: "All of these arguments tending to excuse or justify slavery and the trafficking of Negroes have their responses, and have been refuted by the expert writers and theologians."
Lambruschini felt that the time was propitious for the pope to issue a new statement. Arguing that Pope Gregory should draw on the writings of his predecessors, he provided the pope and the cardinals with the copies of relevant papal pronouncements and the Holy Office statements dating back to the 1400's. He also took up the sensitive matter of whom the pope should address. At the time, neither Spain nor Portugal nor any of the Latin American republics had diplomatic relations with the Holy See. [Note 15: "All these countries were controlled by liberal, anticlerical regimes"]. If a letter were directed to the rulers of these states, there was a good chance it would never be published. He noted that a letter could be sent to the bishops of these nations, but he feared such a move would antagonize the political leaders.
When the cardinals met with the pope, they agreed that he should issue a public declaration on the slave trade: it would not be directed to any person or nation in particular, and no reference would be made to Great Britain's role in it. A letter was promptly drafted by one of the cardinals and edited by the pope. In the final version, Gregory noted that due to the Church's influence, "there were no slaves allowed amongst the great majority of the Christian nations" in the Middle Ages. Subsequently, however, Christians, motivated by sheer greed, began to traffic in Indians and Negroes. This trade had been repeatedly condemned by the Holy See. He listed five of his predecessors who had forbidden it: Pius II (1462), Paul III (1537), Urban VIII (1639), Benedict XIV (1741), and Pius VII (1815). As the practice was still widespread among Christians he felt obligated to add his voice to those of the earlier popes and "vehemently admonish . . . that none henceforth dare to subject to slavery, unjustly persecute, or despoil of their goods, Indians, negroes, or other classes of men." Lay Catholics were informed that they would face excommunication if they disobeyed, and clergy, too, were sternly warned not to oppose this teaching. [...] In December 1839, Pope Gregory XVI issued In Supremo[.]
John Quinn ("'Three Cheers for the Abolitionist Pope!': American Reaction to Gregory XVI's Condemnation of the Slave Trade, 1840-1860"). Bolded emphases added.