General Notes

He was born in 742 to Pepin the Short, who was Mayor of the Palace of Childeric III, the last of an ever degenerating line of Merovingian kings. In 751, with the support of the Pope, Pepin cut off Childeric's long hair, the mark of his kingship, and sent him to a monastery, arrogating to himself the royal power. He was an active ruler, imposing peace on his border-lands, and twice descending on Italy to protect the Pope from the Lombards, giving to him the duchy of Rome as his own state in the bargain.
In 768 Charlemagne and his brother Carloman succeeded to the joint rule of the Franks, but three years later Carloman died, and Charlemagne ruled supreme. He was as active as his father in defending and expanding his territories. In 773, when the Lombards were again putting pressure on the Pope, he crossed the Alps with astonishing speed and defeated the Lombards absolutely, putting their king in a monastery (now a family habit) and assuming the 'Iron' Crown of Lombardy himself.
He now began a systematic campaign to conquer the Saxons, and ten years of the most bitter fighting ensued. The Saxons discovered an able leader in Widukind, and in 782, managed to wipe out a substantial army of Franks. Charlemagne had 4,500 Saxons beheaded at Verden in retribution, and went on to celebrate 'The Nativity of Our Lord and Easter as he was wont to do,' says Einhard, his biographer. It took nearly three years to find Widukind, and he was then baptized---a clear declaration of submission; the rest of the Saxons gave little trouble in taking baptism, or obeying their new Frankish masters---they remembered Verden.
A feudal vassal of Charlemagne who should have learned a lesson from this was Duke Tassilo of Bavaria, but he preferred to behave as if he were independent of his overlord. Charlemagne gave him one chance to reform, but then found that he was plotting with his enemies, so in 788 he too was put into a monastery, and Bavaria was incorporated into the fast growing empire.
In Spain he was not so successful: he had been forced to call off his invasion in 778, for his troops were needed elsewhere, and anyway the Muslims turned out to be not as disunited as he had been told; it was in this retreat that Roland died. But in 793 the Muslims attacked over his borders, so he set up an enclave on the southern side of the Pyrenees to guard the area.
He now turned his attention to the Avars, relations of the Huns, who lived in the area of the middle Danube, and were phenomenally rich with tribute-money they had wrung from the Byzantine Emperors. Peaceful negotiations had failed to keep them from raiding Charlemagne's lands, and so he set out to conquer them. It was as hard a war as that against the Saxons, lasting from 791-9, and Charlemagne was wise to distribute the loot he gained from it to his war-weary people instead of keeping it for himself.
Since 476 there had been no Emperor in the West, and until recently the Popes had looked to the Byzantine Emperors for protection. In 800 the Pope was set upon and deposed, and Charlemagne had to go do to Rome to restore him. On Christmas Day of that year he was praying in St. Peter's when the Pope came up and crowned him as Emperor, taking him 'unawares.' Historians wrangle over the coronation of Charlemagne, and the results of their searches read like detective stories. Suffice it to say that Charlemagne must have known what was going to happen, but he was rather disturbed about the whole thing afterwards; possibly he was upset at not having the fiat of the Emperor of the East, though a woman was reigning there at the time, possibly he felt the Pope had arrogated to himself too great a part in the coronation. Certainly he kept a very healthy respect for the Byzantine Empire, though he was not a man to fear another's power: he had good relations with Haroun-al-Rashid, the Caliph of Baghdad, who sent him a white elephant, and arranged protection for pilgrims visiting Jerusalem, in the heart of Musl