The papal theory embodied in the _Donation of Constantine_ was obviously crammed with seeds of future strife; for the present, however, the fortunes of the House of Pippin and of the Papacy were bound together in amity. The constant accession of strength to the former and of prestige to the latter made them the central figures of European politics. The new political form to which their union gave birth slowly shaped itself. In Italy the first step was to get rid of the Lombards. On the death of the Lombard King, Aistulf, there were two claimants for the throne. One of the two, Desiderius, secured the Pope's help by the promise of ceding more cities, and became king. The Pope, writing to Pippin, says: "Now that Aistulf, that disciple of the devil, that devourer of Christian blood is dead; and that by your aid and that of the Franks [a complimentary phrase, for Pippin seems to have done nothing] he is succeeded by Desiderius, a most gentle and good man, we pray you to urge him to continue in the right way." But the "most gentle and good" Desiderius strayed from the right way, and did not cede the promised cities. So the Pope besought Pippin to use force; but Pippin thought that he had done enough, and the Pope was obliged to rest content. Pippin died in 768. One can imagine the consternation at Rome on Pippin's death to learn that the dowager queen of the Franks was arranging a marriage between her son Charlemagne and a daughter of Desiderius, and another marriage between her daughter and a son of Desiderius. The Pope wrote in terror that the plan was of the devil, and forbade it under the pains of everlasting damnation; nevertheless, Charlemagne married the daughter of Desiderius (770). The Pope's anticipations, however, were not justified; the horrible union of the House of Pippin with the "unspeakable" Lombards came to an abrupt end. Charlemagne, probably from personal dislike, put away his wife, and sent her ignominiously back to her father. Desiderius, angry at the insult, rushed upon his fate; he not only intrigued in Frankish affairs against Charlemagne, but he also seized many of the cities given to the Pope by the _Donation of Pippin_. He invaded the duchy of Rome, and advanced within fifty miles of the city. This time Charlemagne acted in conformity with the papal entreaties. He crossed the Alps, routed the Lombard army, captured Pavia, took Desiderius prisoner and assumed the title of King of the Lombards (773-774). He went on to Rome, and solemnly confirmed the _Donation of Pippin_, and also made a further _Donation_. This latter _Donation_, which led to disputes between the Papacy and Charlemagne's successors, is a matter of great uncertainty. Subsequent papal advocates claimed that it embraced two thirds of Italy. Probably Charlemagne only intended to restore to the Papacy its private property scattered throughout northern and central Italy, which had been seized by the Lombards.