Of all the neighbours of king Charles, it was Desiderius the Lombard who was first destined to feel the weight of the Frankish sword. He had not only received Carloman’s widow Gerberga, when she fled from Burgundy, but had shown some intention of proclaiming her son king of the Franks. Yet it was not this machination against Charles that was the actual cause of war, but the relations of the Papacy with Desiderius. Hadrian I. had just been raised to the Papal throne. He was a Roman by birth, and a great hater of the Lombards. [Sidenote: Quarrel of the Pope and the Lombards.] He refused the friendship and alliance which Desiderius proffered, and very shortly after he was consecrated began to pick a quarrel with the unfortunate king. He demanded from him the important towns of Ferrara and Faenza, as part of the Exarchate of Ravenna. They had been promised to St. Peter, he said, in 757, while Desiderius was struggling for the crown with king Ratchis, and must be handed over at once. Desiderius, thinking that Charles would be too much occupied beyond the Alps in settling the newly-annexed dominions of his brother to allow of his appearance in Italy, replied to the Pope’s challenge by sending a host into the Pentapolis, and seizing Sinigaglia and Urbino. Shortly afterwards he raised the full force of the Lombard realm, and marched against Rome. Hadrian had expected this. He fortified and strongly garrisoned the city, and sent in haste to bid the lord of the Franks to come to the help of St. Peter, and force the unrighteous Lombards to carry out in full the treaty that king Pippin had imposed upon them. The news of the despatch of this embassy seems to have frightened Desiderius. He drew back to Viterbo, and, instead of pressing the siege of Rome, sent an embassy to Charles, to explain that the Pope’s charges were unfounded, as he was not keeping back anything that really belonged to the Exarchate (772, autumn).