ANTONELLI, LEONARDO. — Cardinal, b. at Senigallia on 6 Nov. 1730, d. there on 23 Jan. 1811. After serving as secretary of the Cifra and prefect of Castel S. Angelo, he was secretary of the Conclave that resulted in the election of Clement XIII (1758) and composed a diary of the historic event. Appointed assessor of the Holy Office in 1766, he was required to examine the book by Febronius, denouncing its jurisdictionalist maxims. Pius VI, in the first consistory of 24 Apr. 1775, created him cardinal, assigning him the title of S. Sabina. In 1780 he became prefect of the Congregation for the Propagation of the Faith, negotiating with Russia for the organization of Polish dioceses and achieving the erection of the archbishopric of Mohilev. Having become bishop of Palestrina in 1794, he was a benefactor of that ancient suburbicarian see. In Rome he established four nocturnal oratories. During the Roman Republic, on 6 Feb. 1798, A. was arrested and imprisoned in the Convent prison, where he was offered the chance to renounce his cardinalate. On that occasion, he displayed intrepid apostolic courage. Sent to Civitavecchia, he was able to reach Monte Argentaro. Expelled thence, he took refuge in Castro. After 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 in the following year was named Major Penitentiary and archpriest of the Archbasilica of the Lateran.
A. took an active part in the discussions that led to the stipulation of the Concordat with France and was president of the commission charged with examining the draft concordat for the Kingdom of Italy. He accompanied Pius VII to Paris on the journey for Napoleon’s coronation, in the capacity of 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. was arrested by a detachment of dragoons and sent first to Spoleto, then to Macerata, and finally to Senigallia, where death overtook him.
Among his writings are to be recalled the Memorie storiche delle sacre teste dei ss. Apostoli Pietro e Paolo della loro ricognizione nella Basilica lateranense (Rome 1803).
BIBL. F. Cancellieri, Cenotaphium Leonardi Antonelli Cardinalis, Pesaro 1825; G. Moroni, Dizionario di erudizione storico-ecclesiastica, II, Venice 1840, p. 217; I. Rinieri, La diplomatica pontificia nel sec. XIX, Rome-Turin 1902-1906; C. Gendry, Pie VI, sa vie, son pontificat, Paris 1906; P. Richard, s. V. in DHG, I, cols. 838-40; J. Schmidlin, Histoire des Papes de l'époque contemporaine, I, Lyons 1938 (Fr. trans.). Mario de Camillis