778 - 840
Louis I, the Pious, was the son of Charlemagne and he was the last ruler to maintain the unity of the Carlongian empire.
He was crowned emperor by the pope at Reims in 816. His eldest son Lothar was crowned co-emperor and the younger sons (Pepin, and Louis, the German) were allocated parts of the empire. This led to tensions within the family that were to beset Louis for the remainder of his life. Deposed by his sons twice, he was restored to the throne each time.
But after his death civil war between
the brothers broke out and the empire was split into the Middle kdm,
the East Frankish Kdm, and the West Frankish kdm.