Upon his brother’s death, Charlemagne repudiated Desiderata (she had produced no children anyway) and sent her back to her father’s court—there was no more need for a Lombard alliance, and so there was no more need for a Lombard princess. He quickly remarried to a 13-year-old Swabian named Hildegard; his marriage to her secured the eastern region and strengthened his position. This sort of ruthlessness became Charlemagne’s trademark response in times of danger for his lands—that and his determination, a cold rationalization of events and actions, and tireless focus on administration. It was now his time to secure his power and his own dynasty, and that is exactly what he focused on for the next 10 years.
Einhard, his biographer, knew Charlemagne only in the later part of his life, but it seems that his later character shows the reasons for his earlier successes:
Charlemagne was by far the most able and noble-spirited of all those who ruled over the nations in this time. He never withdrew from an enterprise that he had once begun and was determined to see through to the end, simply because of the labor involved; and danger never deterred him. Having learnt to endure and suffer each particular ineluctable circumstance, whatever its nature might be, he was never prepared to yield to adversity; and in times of prosperity he was never to be swayed by the false blandishments of fortune. (63-64)
Einhard, in sum, attributes Charlemagne’s success to his indomitable strength of will.
Carloman had left two sons, and by law they should have inherited their father’s lands, but their mother, Queen Gerberga, did not wait to find out what Charlemagne’s intentions were—she fled to Lombardy and put them under the protection of Desiderius to save their lives. Meanwhile, Charlemagne began to bargain with Carloman’s supporters: some readily transferred their allegiance, some had to be bribed, and some had to be made kin, thus his marriage to Hildegard.
His next problem would be what to do with the Lombards and to settle his affairs with the papacy—but first he had to deal with the Saxon problem. Francia’s ancient enemy, the Saxons, held the lands along his northern border, and there was little to no negotiating with them—they were steadfastly pagan, they were constantly looking for better farmlands than the cold northern mountains, and they had little respect for negotiation or paying tribute. The moment the Saxons knew Carloman died and there was a potential for weakness, they attacked. In 772, Charlemagne hit back by attacking the religious icon of the Irminsul (a vast, ancient tree trunk erected in the open air as a pillar: it was a shrine, believed to be one of the pillars of the heavens) and destroying it. In one strike, he wanted to prove that his military might was superior, and that his Frankish God was also superior.
Now he could focus on ending the three-way conflict in Italy between the papacy, Lombardy, and Francia. Pope Stephen died and Pope Hadrian I succeeded him in 772, and Hadrian was made of sterner stuff than Stephen. He demanded the return of certain cities in Lombardy that Desiderius currently controlled; Desiderius denied the pope’s charges and instead took over more papal cities and began heading toward Rome. Charlemagne crossed the Alps, and over the winter of 773 he laid siege to Pavia, the Lombard capital—and it was not until the spring of 774 that the city fell and Desiderius was exiled to a monastery. While he was waiting for Pavia to succumb, Charlemagne visited the pope and received a warm welcome, as the king not only was a firm supporter of the papacy but also was about to remove one of the enemies of the pope himself. Hadrian granted him the title of “patrician,” and Charlemagne confirmed and expanded his father’s grants of land, adding to the list Tuscany, Emilia, Venice, and Corsica. When Pavia fell, Charlemagne took for himself the Iron Crown of Lombardy (so named because a supposed nail from the True Cross was worked into the golden circlet), making him not only king of the Franks but also king of the Lombards—and so in less than two years his reputation showed he was a hugely successful and new kind of king.
Charlemagne’s relationship with Pope Hadrian I was a warm and respectful one, but it is clear from the chroniclers that a lot of it was window dressing. The king was a dutiful son to his holy father, but beyond that he was going to set his own agenda. Hadrian tried to manipulate Charlemagne into more military work, but Charlemagne refused, saying he had to return to his fight with the Saxons. The balance of spiritual and temporal power was a tricky thing, and the pope realized too late that he had exchanged one kind of master (the Lombards) for another (the Franks). Hadrian protested, and he was perfectly within his rights as he had been given the authority by the papacy to dictate, in the name of God, what kings and emperors should or should not do. Charlemagne operated under the idea of divine sanction, in that as a king he and his heirs were allowed to rule, under God, all the affairs of their subjects, both clergy and laymen. Hadrian had to give way as the king left to go north, and Charlemagne won this round—but it was a contest that would be fought between rulers and popes for centuries.