Timeline:

742: Charlemagne born.
768: Charlemagne and Carloman rule together.
771: Charlemagne becomes sole ruler of the thrown.
772: Charlemagne begins war with the Saxons.
782: Charlemagne orders the deaths of 4,500 Saxons in an attempt to convert them to Christianity.
788: Charlemagne conquers the Bavarian tribe, bringing all Germanic territories into one.
789: Admonitio generalis written as a new set of laws for the empire.
800: Charlemagne crowned Holy Roman Emperor by the Pope.
804: End of Saxon war
813: Charlemagne crowns his son Louis.
814: Charlemagne dies.