(17 Aug. 1740–3 May 1758)
Born at Bologna on 31 Mar. 1675, of noble but impoverished parentage, Prospero Lorenzo Lambertini studied at the Collegio Clementino, Rome, taking his doctorate in theology and law in 1694. Outstanding in ability and juridical training, he rose rapidly in the curia, becoming secretary of the Congregation of the Council in 1720. As Promotor of the Faith 1708–27 he had charge of canonizations, and wrote a classic treatise on the subject (De servorum Dei beatificatione et beatorum canonizatione: 1734–8) marked by a fresh, historical approach, reflecting his interest in archaeology and the researches of the Maurists; it remains an indispensable study. Benedict XIII, whose close adviser he was, promoted him titular bishop of Theodosia (1724), archbishop of Ancona (1727), and cardinal (in petto in Dec. 1726 and publicly in Apr. 1728). Translated to Bologna in 1731, he proved an efficient, greatly loved pastor, but found time to write a pioneer study of diocesan synods—which could not be published until 1748—as well as works on the feasts of Jesus Christ and of the BVM and on the mass. At the six-month conclave of 1740, the longest in modern times, he was not considered until the last moment, when he was elected as a compromise to everyone's surprise.
The choice was fortunate, for Benedict combined an unusually sympathetic personality with a high degree of political realism and chose highly capable collaborators. Conciliatory by nature and conviction, he concluded concordats containing substantial concessions with Sardinia (1741), Naples (1741), Spain (1753), and Austria for Milan (1757). The one with Spain, which surrendered practically all church appointments to the crown, was the most far-reaching. In the same spirit he restored relations with Portugal, disrupted since Benedict XIII's time, granting King John V (1706–50) the title ‘Most Faithful’ and conceding his most exorbitant demands for control of church affairs. He was no less accommodating, in the interests of their Catholic subjects, with Protestant sovereigns. Thus he cultivated good relations with Frederick II of Prussia (1740–86), which through the conquest of Silesia had significantly increased its Catholic population, and acknowledged his title as king, denied him by previous popes. As a result of this rapprochement he was able to prevent the setting up of a Prussian state church, with its own vicar-general and effectively independent of the holy see. His acceptance of these arrangements, often criticized as weakness, was proof of his awareness of what was possible in a world of absolutist states. His touch was less sure in dealing with the complex situation arising out of the death of Emperor Charles VI (20 Oct. 1740) and the War of the Austrian Succession (1740–8). First, he irritated Maria Theresa of Austria (1740–80) by only belatedly (20 Dec. 1740) recognizing her hereditary right to the imperial title, an act which aroused considerable opposition, and then deepened the estrangement by recognizing (Feb. 1742) Charles Albert of Bavaria as Emperor Charles VII (1742–5). As a result he had to witness the sequestration of all benefices in Austria, and the invasion of the papal states by warring troops. On Charles VII's death (Jan. 1745) he assumed a neutral stance and in Dec. 1745, in spite of pressure from France and Spain, recognized Francis I, consort of Maria Theresa, as emperor (1745–65). In the peace of Aachen (1748) Parma and Piacenza were disposed of without regard to the feudal rights of the holy see, Benedict's protest being merely noted as a dissenting view.