LOUIS I. (778–840), surnamed the “Pious,” Roman emperor, third son of the emperor Charlemagne and his wife Hildegarde, was born at Chasseneuil in central France, and crowned king of Aquitaine in 781. He received a good education; but as his tastes were ecclesiastical rather than military, the government of his kingdom was mainly conducted by his counsellors. Louis, however, gained sound experience in warfare in the defence of Aquitaine, shared in campaigns against the Saxons and the Avars, and led an army to Italy in 792. In 794 or 795 he married Irmengarde, daughter of Ingram, count of Haspen. After the deaths of his two elder brothers, Louis, at his father’s command, crowned himself co-emperor at Aix-la-Chapelle on the 11th of September 813, and was formally associated in the government of the Empire, of which he became sole ruler, in the following January. He earned the surname of “Pious” by banishing his sisters and others of immoral life from court; by attempting to reform and purify monastic life; and by showing great liberality to the church. In October 816 he was crowned emperor at Reims by Pope Stephen IV.; and at Aix in July 817, he arranged for a division of his Empire among his sons. This was followed by a revolt of his nephew, Bernard, king of Italy; but the rising was easily suppressed, and Bernard was mutilated and killed. The emperor soon began to repent of this cruelty, and when his remorse had been accentuated by the death of his wife in 818, he pardoned the followers of Bernard and restored their estates, and in 822 did public penance at Attigny. In 819 he married Judith, daughter of Welf I., count of Bavaria, who in 823 bore him a son Charles, afterwards called the Bald. Judith made unceasing efforts to secure a kingdom for her child; and with the support of her eldest step-son Lothair, a district was carved out for Charles in 829. Discontent at this arrangement increased to the point of rebellion, which broke out the following year, provoked by Judith’s intrigues with Bernard, count of Barcelona, whom she had installed as her favourite at court. Lothair and his brother Pippin joined the rebels, and after Judith had been sent into a convent and Bernard had fled to Spain, an assembly was held at Compiègne, when Louis was practically deposed and Lothair became the real ruler of the Empire. Sympathy was, however, soon aroused for the emperor, who was treated as a prisoner, and a second assembly was held at Nimwegen in October 830 when, with the concurrence of his sons Pippin and Louis, he was restored to power and Judith returned to court.
Further trouble between Pippin and his father led to the nominal transfer of Aquitaine from Pippin to his brother Charles in 831. The emperor’s plans for a division of his dominions then led to a revolt of his three sons. Louis met them in June 833 near Kolmar, but owing possibly to the influence of Pope Gregory IV., who took part in the negotiations, he found himself deserted by his supporters, and the treachery and falsehood which marked the proceedings gave to the place the name of Lügenfeld, or the “field of lies.” Judith, charged with infidelity, was again banished; Louis was sent into the monastery of St Medard at Soissons; and the government of the Empire was assumed by his sons. The emperor was forced to confess his sins, and declare himself unworthy of the throne, but Lothair did not succeed in his efforts to make his father a monk. Sympathy was again felt for Louis, and when the younger Louis had failed to induce Lothair to treat the emperor in a more becoming fashion, he and Pippin took up arms on behalf of their father. The result was that in March 834 Louis was restored to power at St Denis; Judith once more returned to his side and the kingdoms of Louis and Pippin were increased. The struggle with Lothair continued until the autumn, when he submitted to the emperor and was confined to Italy. To make the restoration more complete, a great assembly at Diedenhofen declared the deposition of Louis to have been contrary to law, and a few days later he was publicly restored in the cathedral of Metz. In December 838 Pippin died, and a new arrangement was made by which the Empire, except Bavaria, the kingdom of Louis, was divided between Lothair, now reconciled to his father, and Charles. The emperor was returning from suppressing a revolt on the part of his son Louis, provoked by this disposition, when he died on the 20th of June 840 on an island in the Rhine near Ingelheim. He was buried in the church of St Arnulf at Metz. Louis was a man of strong frame, who loved the chase, and did not shrink from the hardships of war. He was, however, easily influenced and was unequal to the government of the Empire bequeathed to him by his father. No sustained effort was made to ward off the inroads of the Danes and others, who were constantly attacking the borders of the Empire. Louis, who is also called Le Débonnaire, counts as Louis I., king of France.
See Annales Fuldenses; Annales Bertiniani; Thegan, Vita Hludowici; the Vita Hludowici attributed to Astronomus; Ermoldus Nigellus, In honorem Hludowici imperatoris; Nithard, Historiarum libri, all in the Monumenta Germaniae historica. Scriptores, Bände i. and ii. (Hanover and Berlin, 1826 fol.); E. Mühlbacher, Die Regesten des Kaiserreichs unter den Karolingern (Innsbruck, 1881); and Deutsche Geschichte unter den Karolingern (Stuttgart, 1886); B. Simson, Jahrbücher des fränkischen Reichs unter Ludwig dem Frommen (Leipzig, 1874–1876); and E. Dümmler, Geschichte des ostfränkischen Reiches (Leipzig, 1887–1888). (A. W. H.*)