Excerpts from Books and Wikipedia
"With his military domination of the Frankish magnates and his close alliance with the papacy, Peppin was able to extend his rule over the whole Frankish kingdom, expanding the military and maintaining a large standing army. . . . Carloman's death in 771 led to the absorption of his kingdoms by Charles. . . . He also instigated a series of political and cultural reforms that are referred to as the Carolingian Renaissance. Charlemagne was crowned Imperator Augustus in St. Peter's Basilica in Rome on December 25, 800 by Pope Leo III in an attempt to restore the Western Roman Empire." [1001 Days]