LOUIS I., LE' DknoNNantE or THE PIOUS (ante), Roman emperor, king of the Franks, 778-840; b. at Casseneuil; son of Charlemagne by his third wife, Hildegarde. Ilis elder brother having died he succeeded his father in 814. He was quite successful for a time, but in 817 he was persuaded to give his three sons, Lothaire, Pepin, and Louis, a share in his dominions, and from this arose complications that finally led to It diSSOIIIIi011 of the empire. Bernard, a nephew of Louis, who had inherited Italy after his father, receiving nothing under the new arrangement, revolted; but the emperor allured him to Chalons, made him a prisoner, put out his eyes, and gave Italy to his sou Lotbaire. In his remorse for this crime the emperor sought consolation in the church, and thence forth was a mere tool in the hands of the priests. In 819 he married a second wife, Judith of Bavaria, who in 823 bore him a, son. known in history as " Charles the bald."
In 829, in the interest of this son, be proposed a new division of the empire; but to this the elder sons objected, and the result was a war which lasted during the remainder of the emperor's life. Twice the father was defeated, taken prisoner, and deposed by his sons; but Lothaire, by his ambition to turn everything to his own account, incurred the hostility of his brothers, who conspired to raise the father again to the throne. On tbe death of Pepin in 838 Louis I. proposed to exclude his elder sons, Lothaire and Louis, from their inheritance, and to give his dotninions to Charles the bald. Against this arrangement Louis revolted, aud was joined by the sons of Pepin. In the midst of the war the emperor died at Ingelheim and was buried at Metz.