ANTONELLI, LEONARDO. — Cardinal, born at Senigallia on 6 November 1730, died there on 23 January 1811. After having been secretary of the Cipher and prefect of Castel S. Angelo, he was secretary of the Conclave that led to the election of Clement XIII (1758) and composed a diary of the historic event. Appointed assessor of the Holy Office in 1766, he had to examine Febronius’s book, denouncing its jurisdictionalist principles. Pius VI, in the first consistory of 24 April 1775, created him cardinal, assigning him the title of S. Sabina. In 1780 he became prefect of the Congregation of Propaganda Fide; he negotiated with Russia for the organization of the Polish dioceses, achieving the establishment of the archbishopric of Mohilew. Having become bishop of Palestrina in 1794, he rendered outstanding service to that ancient suburbicarian see. In Rome he established four night oratories. During the Roman Republic, on 6 February 1798, A. was arrested and confined in the prison of the Convertites, where he was urged to renounce the cardinalate. On that occasion, he was an example of intrepid apostolic courage. Sent to Civitavecchia, he was able to reach Monte Argentaro. After his expulsion, he took refuge in Castro. Following the death of Pius VI, he took part in the Conclave of Venice. In 1800 he opted for the suburbicarian see of Porto and S. Rufina and, the following year, was appointed major penitentiary and archpriest of the Lateran Archbasilica.
A. took an active part in the discussions that led to the signing of the Concordat with France and was president of the commission charged with examining the draft concordat for the Italian Kingdom. He accompanied Pius VII to Paris on the journey for Napoleon’s coronation, in his capacity as pro-secretary of State. In 1807 he became bishop of Ostia and Velletri, dean of the Sacred College, and secretary of the Congregation of the Holy Office. During the Napoleonic occupation, A., arrested by a detachment of dragoons, was sent first to Spoleto, then to Macerata and to Senigallia, where death overtook him.
Among his studies, mention should be made of the Memorie storiche delle sacre teste dei ss. Apostoli Pietro e Paolo e della loro ricognizione nella Basilica lateranense (Rome 1803).