Charlemagne (c. 1st of April, 747 – 28th of January, 814) (or Charles the Great, in German Karl der Große, in Latin Carolus Magnus, giving rise to the adjective form 'Carolingian'), was king of the Franks from 771 to 814, nominally King of the Lombards, and Holy Roman Emperor – Imperator and Augustus.
On the death of Pepin the kingdom was divided between Charlemagne and his brother Carloman (Carloman ruled Austrasia). Carloman died on the 5th of December, 771, leaving Charlemagne the leader of a reunified Frankish kingdom. Charlemagne was engaged in almost constant battle throughout his reign. He conquered Saxony in the 8th century, a goal that had been the unattainable dream of Augustus. It took Charlemagne more than 18 battles to win this victory. He proceeded to force Catholicism on the conquered, slaughtering those who refused to convert. He dreamed of the reconquest of Spain, but never fully succeeded in this goal.
In 800, at Mass on Christmas day in Rome, Pope Leo III crowned Charlemagne emperor, a title that had been out of use in the West since the abdication of Romulus Augustulus in 476. While this title helped to make Europe independent of Constantinople, Charlemagne did not use the title until much later, as he feared it would create dependence on the Pope.
Pursuing his father's reforms, Charlemagne did away with the monetary system based on the gold sou. Both he and King Offa of Mercia took up the system set in place by Pippin. He set up a new standard, the livre (i.e. pound)- both monetary and unit of weight- which was worth 20 sous (as per the solidus, and later the shilling) or 240 deniers (as per the denari, and eventually the penny). During this period, the livre and the sou were counting units, only the denier was a coin of the realm.
Charlemagne applied the system to much of the European Continent, and Offa's standard was voluntarily adopted by much of England.
Charlemagne organized his empire into 350 counties, each led by an appointed count. Counts served as judges, administrators, and enforced capitularies. To enforce loyalty, he set up the system of Missi Dominici, meaning 'Envoys of the Lord'. In this system, one representative of the church and one representative of the emperor would head to the different counties and every year report back to Charlemagne on their status.
When Charlemagne died in 814, he was buried in his own Cathedral at Aachen. He was succeeded by his only son to survive him, Louis the Pious, after whose reign the empire was divided between his three surviving sons according to Frankish tradition. These three kingdoms would be the foundations of later France and the Holy Roman Empire.