Aistulf, also called Aistulf of Friuli, (d. 756) was king of Lombards (749-756) and duke of Spoleto (751-756).
After he succeded Ratchis as the king of Lombardy in 749, Aistulf continued the policy of expansion and raids against popes and the Byzantineexarchs of Italy. In 751, he captured Ravenna. He even threatened Rome itself, and claimed a capitation tax.
The popes, thoroughly irritated and alarmed, and hopeless of aid from the Byzantine empire, turned to the Carolingian mayors of the palace of Austrasia, the effective rulers of the Frankish kingdom. In 741, pope Gregory III asked Charles Martel to intervene, but he was to busy elsewhere and declined. In 753, pope Stephen III visited Charles Martel's son Pippin the Short, who had proclaimed himself king of the Franks in 751. In return for the transfer by the pope of the Frankish crown from the decayed line of Clovis to his own, Pippin crossed the Alps, defeated Aistulf and gave to the pope the lands which Aistulf had torn from the empire.
Aistulf died hunting in 756. He was succeded by Desiderius as king of Lombardy and by Alboin as duke of Spoleto.
STEPHEN II., pope from March 752 to April 757, was in deacon's orders when chosen to the vacant see within twelve days after the death of Zacharias.' The main difficulty of his pontificate was in connexion with the aggressive attitude of Aistulf, king of the Lombards.
After unsuccessful embassies to Aistulf himself and appeals to the emperor Constantine, he, though in feeble health, set out to seek the aid of Pippin, by whom he was received in the neighbourhood of Vitry le Brule in the beginning of 754.
The result of his negotiations was the Frankish invasion of Aistulf's territory and the famous "donation" of Pippin.
The winter passed with the Romans anxiously awaiting the descent of Aistulf's army with the first good days of spring From the emperor -- Constantine V -- all that came was an order to the pope to negotiate with Aistulf for the restoration of Ravenna.
Aistulf refused, and in two great assemblies of the Franks (at Braisne on March 1 and at Kiersy-sur-Oise on April 14, 754) it was agreed-not without opposition -- that the Lombards should be compelled by force of arms.
Aistulf made over Narni to Pepin's representatives, and waited until Pepin and his army were safely over the Alps.