BBC - History - Charlemagne

On October 9, 768 Charlemagne and his brother Carloman I were crowned Kings of the Franks. From the article:

"Charlemagne (Charles the Great) was king of the Franks and Christian emperor of the West. He did much to define the shape and character of medieval Europe and presided over the Carolingian Renaissance.

Charlemagne was born in the late 740s near Liège in modern day Belgium, the son of the Frankish king Pepin the Short. When Pepin died in 768, his kingdom was divided between his two sons and for three years Charlemagne ruled with his younger brother Carloman. When Carloman died suddenly in 771, Charlemagne became sole ruler.

Charlemagne spent the early part of his reign on several military campaigns to expand his kingdom. He invaded Saxony in 772 and eventually achieved its total conquest and conversion to Christianity. He also extended his dominance to the south, conquering the kingdom of the Lombards in northern Italy. In 778, he invaded northern Spain, then controlled by the Moors. Between 780 and 800, Charlemagne added Bohemia to his empire and subdued the Avars in the middle Danube basin to form a buffer state for the eastern border of his empire.

In 800 a rebellion against Pope Leo III began. Charlemagne went to his aid in Rome and defeated the rebellion. As a token of thanks, Leo crowned Charlemagne on Christmas Day that year, declaring him emperor of the Romans. Although this did not give Charlemagne any new powers, it legitimised his rule over his Italian territories and attempted to revive the imperial tradition of the western Roman emperor.

The immense territories which Charlemagne controlled became known as the Carolingian empire. Charlemagne introduced administrative reforms throughout the lands he controlled, establishing key representatives in each region and holding a general assembly each year at his court at Aachen. He standardised weights, measures and customs dues, which helped improve commerce and initiated important legal reforms. He also attempted to consolidate Christianity throughout his vast empire. He persuaded many eminent scholars to come to his court and established a new library of Christian and classical works.

Charlemagne died in 814. His successors lacked his vision and authority, and his empire did not.