When the Popes sought help against the Lombards, it was to Charlemagne as to his father Pepin that they naturally turned. Charlemagne had hoped at the beginning of his reign to maintain a friendship with King Didier of Lombardy and had even married his daughter, an alliance that roused the Pope of that date to demand in somewhat violent language: ‘Do you not know that all the children of the Lombards are lepers, that the race is outcast from the family of nations? For these there is neither part nor lot in the Heavenly Kingdom. May they broil with the devil and his angels in everlasting fire!’
Charlemagne went his own way, in spite of papal denunciations; but he soon tired of his bride, who was plain and feeble in health, and divorced her that he might marry a beautiful German princess. This was, of course, a direct insult to King Didier, who henceforth regarded the Frankish king as his enemy; and Rome took care that the gulf once made between the sovereigns should not be bridged.
In papal eyes the Lombards had really become accursed. It is true that they had been since the days of Gregory the Great orthodox Catholics, that their churches were some of the most beautiful in Italy, their monasteries the most famous for learning, and Pavia, their capital, a centre for students and men of letters. Their sin did not lie in heretical views, but in the position of their kingdom that now included not only modern Lombardy in the north, but also the Duchy of Spoletum in South Italy. Between stretched the papal dominions like a broad wall from Ravenna to the Western Mediterranean; and on either side the Lombards chafed, trying to annex a piece of land here or a city there, while the Popes watched them, lynx-eyed, eager on their part to dispossess such dangerous neighbours, but unable to do so without assistance from beyond the Alps.
Soon after the death of his younger brother Charlemagne was persuaded to take up the papal cause and invade Italy. At Geneva, where he held the ‘Mayfield’ or annual military review of his troops, he laid the object of his campaign before them, and was answered by their shouts of approval.
It was a formidable host, for the Franks expected every man who owned land in their dominions to appear at these gatherings prepared for war. The rich would be mounted, protected by mail shirts and iron headpieces, and armed with sword and dagger; the poor would come on foot, some with bows and arrows, others with lance and shield, and the humblest of all with merely scythes or wooden clubs. Tenants on the royal demesnes must bring with them all the free men on their estates; and while it was possible to obtain exemption the fine demanded was so heavy that few could pay it.
When the army set out in battle array, it was accompanied by numerous baggage-carts, lumbering wagons covered with leather awnings, that contained enough food for three months as well as extra clothes and weapons. It was the general hope that on the return journey the wagons would be filled to overflowing with the spoils of the conquered enemy.
The Lombards had ceased, with the growth of luxury and comfortable town life, to be warriors like the Franks; and Charlemagne met with almost as little resistance as Pepin in past campaigns. After a vain attempt to hold the Western passes of the Alps, Didier and his army fled to Pavia, where they fortified themselves, leaving the rest of the country at the mercy of the invaders.
Frankish chroniclers in later years drew a realistic picture of Didier, crouched in one of the high towers of the city, awaiting in trembling suspense the coming of the ‘terrible Charles’. Beside him stood Otger, a Frankish duke, who had been a follower of the dead Carloman and was therefore hostile to his elder brother. ‘Is Charles in that great host?’ demanded the King continually, as first the long line of baggage-wagons came winding across the plain, and then an army of the ‘common-folk’, and after them the bishops with their train of abbots and clerks. Every time his companion answered him, ‘No! not yet!’
‘Then Didier hated the light of day. He stammered and sobbed and said, “Let us go down and hide in the earth from so terrible a foe.” And Otger too was afraid; well he knew the might and the wrath of the peerless Charles; in his better days he had often been at court. And he said, “When you see the plain bristle with a harvest of spears, and rivers of black steel come pouring in upon your city walls, then you may look for the coming of Charles.” While he yet spoke a black cloud arose in the West and the glorious daylight was turned to darkness. The Emperor came on; a dawn of spears darker than night rose on the beleaguered city. King Charles, that man of iron, appeared; iron his helmet, iron his armguards, iron the corselet on his breast and shoulders. His left hand grasped an iron lance ... iron the spirit, iron the hue of his war steed. Before, behind, and at his side rode men arrayed in the same guise. Iron filled the plain and open spaces, iron points flashed back the sunlight. “There is the man whom you would see,” said Otger to the king; and so saying he swooned away, like one dead.’
In spite of this picture of Carolingian might, it took the Franks six months to reduce Pavia; and then Didier, at last surrendering, was sent to a monastery, while Charlemagne proclaimed himself king of the newly acquired territories. During the siege, leaving capable generals to conduct it, he himself had gone to Rome, where he was received with feasting and joy. Crowds of citizens came out to the gates to welcome him, carrying palms and olive-branches, and hailed him as ‘Patrician’ and ‘Defender of the Church’. Dismounting from his horse he passed on foot through the streets of Rome to the cathedral; and there, in the manner of the ordinary pilgrim, climbed the steps on his knees, until the Pope awaiting him at the top, raised and embraced him. From the choir arose the exultant shout, ‘Blessed is he that cometh in the name of the Lord.’