Louis the Pious

Alone among the legitimate sons of Charlemagne, Louis the Pious outlived his father, and so inherited the Frankish empire whole in 814. Born in 778 to Charlemagne and his wife Hildegard, he was made king of Aquitaine as an infant in 781 and governed that subkingdom for three decades. After the deaths of his elder brothers Pepin of Italy and Charles, Charlemagne crowned him co-emperor at Aachen in 813, and he succeeded the following January.

Louis began his reign as a reformer, reorganizing the palace, promoting monastic discipline under the direction of Benedict of Aniane, and attempting to give the empire a durable constitutional shape. His Ordinatio Imperii of 817 made his eldest son Lothair co-emperor and assigned subordinate kingdoms to the younger sons Pepin and Louis the German, in the hope of preserving imperial unity across the generations. His nephew Bernard, king of Italy, rose against the settlement; the revolt failed, and Bernard died after being blinded, an act for which the emperor performed public penance at Attigny in 822.

The succession scheme was unsettled by Louis's second marriage. His first wife, Ermengarde of Hesbaye, died in 818, and in 819 he married Judith, daughter of the Bavarian count Welf. The birth of their son Charles, later called the Bald, in 823 required provision that could only come at the elder sons' expense, and resentment hardened into rebellion. The sons rose in 830 and again in 833, when Louis's army deserted him near Colmar at the encounter remembered as the Field of Lies; he was deposed and subjected to public penance at Soissons. The victors soon quarreled, and Louis was restored in 834.

His final years were spent redrawing the partition of the empire as circumstances shifted, particularly after the death of his son Pepin of Aquitaine in 838. Louis died in June 840 on an island in the Rhine near Ingelheim and was buried at Metz. The war that followed among Lothair, Louis the German and Charles the Bald ended with the Treaty of Verdun in 843, which divided the Carolingian empire into three kingdoms and traced the rough outlines of later France and Germany.