To the Frankish delegates who appeared in Rome to investigate the condition of affairs between the Pope and Desiderius, Hadrian probably explained that his difficulties had been occasioned by his refusal to anoint the pretenders, Carloman’s sons, at Desiderius’ request. There would not be wanting, also, appeals to Charles to fulfil his solemn engagements to stand by the Roman See. Desiderius, in his interview with the envoys, treated them curtly; he was evidently looking forward to settling the issue with Charles by arms. There was not only the difference with the Pope, due to Lombard aggression on the papal cities, but he must have felt aggrieved because Charles had refused to live with his daughter. There was also the fact that at the court of the Lombard king, Carloman’s children had been received and were being used in the rôle of pretenders, as tools in an intrigue against the ruler of the Franks.
Desiderius had prepared for invasion from the North by fortifying the pass at Susa, the “débouchement” in northwestern Italy of the road regularly taken by the Frankish army when they invaded Italy. But while methods of military defense were being looked to, Desiderius saw the need of preparing for the coming struggle by consolidating his rule over his adherents and dependents. The important Duchy of Benevento was allied with him by the bonds of family relationship. The Duchy of Spoleto was less important, as it had lost in territory and in independence during the reign of Desiderius, but means were taken to conciliate the Church by gifts to important abbeys. Indeed, so numerous were these alienations of the royal lands to ecclesiastical foundations, that the king’s policy in annexing cities and territories in the Patrimony of the Pope had become as much an economic as a political necessity, for the owners of the alienated land could only in this way be compensated for their losses. The abbeys were of strategic importance; many of them, and these the largest, were situated on the inner lines of communication. The cities and castles were still surrounded with their Roman walls, and under the Lombard monarchy the many roads and bridges had been kept in order.
On the other side of the Alps, there was less unanimity as to the necessity of the Frankish army passing the frontier. Charles’ plan of intervention was agreed to by the Frankish nobles, though the opposition against an Italian expedition had always before in Pippin’s day had a strong backing. But, in order to show a temper amenable to compromise, Charles offered to continue peaceful relations with Desiderius, on condition that the sum of 14,000 solidi be given as an indemnity to the Franks. This offer was refused. A general assembly of the Frankish host was held at Geneva by Charles, and after dividing it into two parts, the army passed over into Italy by Mont Cenis and by the Great St. Bernard. Again Charles stopped to treat with Desiderius, but to no purpose.
The Lombards withdrew from their strongly fortified position where the Alpine passes widen out into valleys, and it was rumored that the Frankish army, aided by Lombard treachery, had found by-paths to avoid the strongly held Lombard camps and had marched down into the plain after Charles had stayed some time at Novalese, an abbey richly endowed by his family, where he took provisions for his march.
In the meantime, Desiderius had fled to Pavia, his capital, preparing for a long siege. Most of his army was now scattered; a portion of it retreated, accompanying his son Adalghis, with the widow of Carloman and her children, to Verona, the strongest of the Lombard citadels. But the Lombard resistance was most ineffective; the Beneventines apparently took no part in the wars, while the people of the Spoletan duchy, deserting their duke, took the oath of allegiance to Hadrian, and many places in central Italy surrendered to the Pope.
Charles began the siege of Pavia at the end of September, purposing by the capture of their chief city to end completely the dominion of the Lombards, and so to finish the work left half done by his father. Leaving the bulk of his army in front of the walls of Pavia, he took a division of Frankish troops and entered Verona without opposition. Adalghis fled to Constantinople. Carloman’s wife and heirs were now in the hands of the conquerors.
There was no longer fear of opposition from other Lombard towns. The siege had already lasted six months, but the town was well provided with food, and was too strong to be taken by assault. Charles now left the siege with a large escort in order to celebrate the Easter festival at Rome. He was the first Frankish sovereign who had visited the city. Pippin, his father, notwithstanding his close alliance with the Church, had always scrupulously avoided making the pilgrimage to Rome, probably because he did not desire to pass through Lombard territories.
Charles was received with the honors ordinarily given to the Exarch of Ravenna. As he entered St. Peter’s, the choir sang the anthem, “Blessed is He that Cometh in the Name of the Lord,” and there were many public demonstrations of friendship between the Pope and the King. But it is worth noting that Charles asked the Pope’s permission to enter the city, and great care had to be taken to prevent acts of violence between the residents of the city and the visitors from the North. The most important step taken before Charles left the city to return to Pavia, was the formal transfer to the Pope of a document signed by Charles and his nobles, authorizing the retention by the Pope of the existing patrimony of the Holy See, and also engaging that all private property belonging to it should be restored.
Pavia held out stoutly, though sorely tried by famine and pestilence; but there was no hope of relief. Finally, Desiderius surrendered his capital and his person at the beginning of June, 774, and with this surrender the independent Lombard monarchy ends. Charles, from this time forth, took the title of King of the Lombards. The Lombard chieftains crowded into the city to do him homage, and when he crossed the Alps, he took with him Desiderius and his family, not forgetting the royal treasury of the Lombards.
Charles had been mindful of his obligations to the Pope, and regarded himself as bound to carry out the policy of his father. But he plainly had no thought of turning over any large share of the territory of the Italian peninsula into the hands of the Roman See. In Rome it seemed to be expected that the friendly and generous ruler from across the Alps would make Hadrian master of the whole of middle Italy. But now that Charles was ruler of the Lombards he showed that in dealing with the Italian situation he did not intend to be guided by idealistic politics. Charles also put an interpretation on his title of Patrician that made it clear he meant to be the predominant factor in the states under the Pope’s control. He behaved as master in cases affecting the Pope’s territory when Hadrian’s rights over Ravenna were resisted by the Archbishop of that city; and he also exercised his sovereign authority over Spoleto when the Duke rose in revolt against the Franks.