?742–814 ad, king of the Franks (768–814) and, as Charles I, Holy Roman Emperor (800–814). He conquered the Lombards (774), the Saxons (772–804), and the Avars (791–799). He instituted many judicial and ecclesiastical reforms, and promoted commerce and agriculture throughout his empire, which extended from the Ebro to the Elbe. Under Alcuin his court at Aachen became the centre of a revival of learning