Louis I, known as Louis the Pious, (born April 16, 778, Chasseneuil, near Poitiers, Aquitaine—died June 20, 840, Petersau, an island in the Rhine River near Ingelheim), Frankish emperor (814–40). The son of Charlemagne, he was crowned coemperor with his father in 813 and became emperor in 814 on his father’s death. As emperor, Louis implemented important religious and cultural reforms and formalized Carolingian relations with the pope. He also introduced a plan of succession that sought to preserve the integrity of the empire while respecting the Germanic tradition of dividing the realm among all heirs. The birth of the future Charles II (Charles the Bald) to his second wife, Judith, and alteration of the plan of succession provided Louis’s older sons and a number of bishops with an excuse for rebellion. Twice deposed by his sons, he recovered the throne each time (830, 834), but at his death his surviving sons indulged in a bloody civil war that left the Carolingian empire in disarray.
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