That winter the pope spent at S. Denis, where he solemnly crowned Pepin and his queen, and Charles and Carloman their children, pronouncing an anathema upon all or any who should ever attempt to elect a king not of their house.  Upon Pepin too he conferred the title of patrician.  Can it be that by this he intended the king of the Franks to be his executor in the exarchate as the exarch had been the executor of the emperor?[1] We do not know; but a little later a document was drawn up in which Pepin declared and enumerated the territories he was ready to secure for the pope.  This document, the Donation of Pepin, would seem to have confirmed in detail and in writing the oath he had sworn to the pope at Ponthion.  Unhappily the document has disappeared, and we can only judge of its contents by what actually happened.

[Footnote 1:  The title patrician was not exclusively borne by the exarch, the Dux Romae, for instance, bore that title in 743.]

The adventure into Italy to which the pope had persuaded Pepin was not universally popular with the Frankish nobles.  We find Pepin attempting to gain his end by negotiation with Aistulf, but all to no purpose, and probably in March 755 the Franks set out with the pope at their head to march into Italy to curb and chastise the Lombard.

The great army of Pepin crossed the Alps by the Mont Cenis, and in what was little more than a skirmish upon the northern side of the pass defeated the Lombard army and proceeded to invest Pavia and ravish the country round about.  Aistulf, who was rather an impetuous than a great soldier, had soon had enough and was ready to entertain proposals for peace.  A treaty was made in which he agreed “to restore” Ravenna and divers other cities, and to attempt nothing in the future against Rome and the Holy See.  This having been decided, the pope took leave of Pepin, who returned to France, and went on his way to Rome.

The pope had won and had really established the Holy See as the heir of the empire; but Aistulf was by no means done with.  He forgot alike his treaty and his promises.  “Ever since the day when we parted,” the pope writes to Pepin and the young kings, his sons Charles and Carloman, “he has striven to put upon us such afflictions and on the Holy Church of God such insults as the tongue of man cannot declare....  You have made peace too easily, you have taken no sufficient security for the fulfilment of the promises you have made to S. Peter, which you yourselves guaranteed by writing under your hand and seal....”

But the Franks were deaf.  An expedition to crush the Lombards was a laborious and an expensive business, and Pepin had much to occupy him at home.