The time was favourable for an aggressive policy, because Roman Italy, led by the pope, rose in rebellion against the Emperor. Common hostility against the Emperor formed a link between Liutprand and Pope Gregory II for a while, but the pope soon came to see clearly that the king near him was more dangerous than the distant Emperor. As a token of friendship Liutprand, following the pope's admonition, restored to him his confiscated patrimony in the Cottian Alps. For the moment peace was only endangered by the duke Romuald II of Benevento, who attacked the castle of Cumae by surprise; but after the duke of Naples, aided by the pope's militia, had regained the place and killed the garrison, the pope even paid Romuald the indemnification which he had offered for a peaceable evacuation, and thereby won his friendship. Meanwhile the duke Faroald of Spoleto began to move as well; Narni was taken, Liutprand occupied Classis, the port of Ravenna, and carried booty and prisoners away. He gained other successes at the cost of the respublica; the frontier castles surrendered to him and so he was able to extend the Lombard boundary to Bologna; Osimo in Pentapolis went over to him as well. Then he turned southwards, and attacked the castle of Sutri by surprise (728); this was too much for the pope; the king approached too nearly his own sphere of action. After Liutprand had been in possession of the castle for one hundred and seventy days, the pope insisted on his "restoring and donating" it to the apostles Peter and Paul. Meanwhile the dukes of Spoleto and Benevento had entered into a league with the pope and defended the frontier of the ducatus Romae against the troops of the Emperor. The new exarch Eutychius, who had landed at Naples, did not succeed in making the two dukes desert the league with the pope; his entreaties had no effect on Liutprand till he offered a very important service to the king, placing his own troops at the king's disposal against the independent dukes, so as to take them in the rear and force them to render homage to the king and send hostages in token of their fidelity. The king repaid this service by leading the exarch to Rome, and as the pope could not think of resistance, he again submitted to the Emperor. But the Lombard troops did not enter the imperial town and Liutprand paid homage to the graves of the Principes apostolorum whom he had never intended to combat (729). So the Italian revolution brought double success to Liutprand: territorial acquisition of land in the north and the two dukes' formal submission in the south; and at the same time he had appeared as principal arbiter in these differences on Italian soil.
Liutprand's next care was to make the two duchies' formal dependency real and effective. When difficulties arose after the death of Romuald II of Benevento (731-732), on account of the succession, he marched on Benevento, carried away the young duke Gisulf for education, and installed his own nephew Gregorius, relying upon his own sovereign power. Nearly at the same time, after a breach of the league with the
