It was not long before Charles saw that he had been outwitted.  An immediate change of his policy was necessary.  In 771 it came with the repudiation of Desiderata, who was sent back to her father’s court at Pavia.  Henceforth Charles and Desiderius were implacable enemies.  And now everything went in favour of the papal policy, just as before everything had seemed to cross it.  Carloman, who had not quarrelled with Desiderius, and might have opposed Charles and changed all the future, suddenly died in December of the year of the quarrel.  Charles became thus sole king of the Frankish nation.  When pope Stephen came to die in February 772 he must have laid him down with a quiet mind.

In Stephen’s stead there was elected as pope a pure Roman, born in the Via Lata of the nobility of the City; he took the famous name of Hadrian I. Desiderius, who had watched with a growing anxiety the amazing policy of Stephen, now turned to his successor, and both demanded and begged a renewal of friendship.  Hadrian answered his ambassador at last with the mere truth.  “How can I trust your king when I recall what my predecessor Lord Stephen of pious memory told me in confidence of his perfidy?  He told me that he had lied to him in everything as to the rights of Holy Church, though he swore upon the body of the Blessed Peter....  Look you, such is the honour of king Desiderius and the measure of the confidence I may repose in him.”

Desiderius’ answer was not to the point.  He seized the cities of Faenza, Ferrara, and Comacchio and ravaged the territory about Ravenna, burned the farms and carried off the cattle.  Then he fell upon the Pentapolis, seized Sinigaglia, Jesi, Urbino, Gubbio, S. Leo, and other “Roman” cities, and indeed possessed himself of everything save only Ravenna and Rimini, and proceeded upon a raid into the duchy of Rome.

The answer of the pope was mild but firm:  mild, for the hour was not yet come; firm, for it would strike ere long.  “Tell your king,” said he, “that I swear in the presence of God that if he choose to restore those cities which in my time he has taken from S. Peter, I will hasten into his presence wherever he may appoint a meeting place, at Pavia, Ravenna, Perugia, or here in Rome, that we may confer together....  But if he does not restore what he has taken away he shall never see my face.”

The hour was not come.  Charles was busy with the Saxon hordes upon the north and east of his kingdom.  It was not till the beginning of January 773 that the pope sent his messenger Peter to summon him to his aid.  Meanwhile, Desiderius marched on Rome.  But even without Charles the pope was not defenceless.  The Vicegerent of God who had without a soldier turned back Attila on the Mincio and had thrust back Liutprand from Rome was not to be at the mercy of such a king as Desiderius.  At Viterbo his messengers, the three bishops of Albano, Palestrina, and Tivoli, met the Lombard king and gave him the pope’s last