ASTOLF, King of the Lombards. - He succeeded his brother Rachis in 749. Resuming the anti-Byzantine policy of his predecessor, before July 751 he had Ravenna occupied, thereby putting an end to the exarchate, and then directed himself toward Rome (752). Stephen II managed to conclude with him a 40-year peace, but A. broke it not even four months later, demanding to subject the Romans to an annual tribute of one gold solidus per inhabitant and to reduce Rome and the surrounding cities under his jurisdiction. No transaction was possible, this time, with the Lombard king: the Pope made a last attempt with him on 14 Oct. 753, going personally to meet him at Pavia, accompanied by the captain of the imperial guard of Constantinople and by two Frankish ambassadors; but A. refused every concession.
Stephen II then proceeded from Pavia to Paris, where Pepin, invested by the Pope with the title of patrician and thereby made defender and protector of the Church of Rome, after repeated and vain attempts to resolve the question peacefully, resolved upon war against the Lombards.
The Franks, having crossed the Mont Cenis, clashed at the Chiuse, near Susa, with the Lombard army and defeated it. A., besieged in Pavia, was forced to come to terms (755), which were: the restitution of Ravenna and of several other cities and the promise no longer to molest the Roman duchy. The lands thus obtained were ceded by Pepin to the Pope. But once the Franks had withdrawn, A. advanced again with his army toward Rome and on 1 Jan. 756 laid siege to the city. Three months later, however, he found himself forced to return to northern Italy to face a second time the Frankish army, which had come again to the aid of Stephen II. The Lombards suffered a new defeat (spring of 756). A. had to surrender this time on terms far harsher than in 755: to restore a greater number of cities, that is the Exarchate and the Pentapolis as they had been reduced after the Lombard conquest (Comacchio, Ravenna and all the country between the Apennines and the sea, from Forlì to Senigallia, excluding Ancona, Faenza, Imola, Ferrara). The keys of the cities were consigned to the Pope together with the act of donation "to St. Peter, to the Holy Roman Republic and to all successive Pontiffs," which was then placed in the Confession of St. Peter.
A. died in 756, a few months after Pepin had withdrawn into France.