Although Louis I, "Louis the Pious" born 778, died June 20, 840, was an able ruler and energetic military commander, his reputation has sufferedbecause he was not as successful as his father, CHARLEMAGNE. Louis was crowned king of Aquitaine at the age of three. In this capacity, afterreaching his majority, he established a vigorous Carolingian presence in Spain. His brothers having died, he was crowned co emperor in 813, and in814 he succeeded Charlemagne as sole ruler of the Frankish empire. Louis sought to develop the imperial ideal, working closely with the church.However, squabbles among his sons for greater shares in what was to be their inheritance led to civil war. In 817, Louis made his eldest son,LOTHAIR I, co emperor and allocated parts of the empire to his other sons, LOUIS THE GERMAN and Pepin. The birth of another son, the futureEmperor CHARLES II, to Louis's second wife, Judith of Bavaria, started the trouble. Louis's attempts to provide for Charles precipitated aseries of revolts by the older sons. The invasions of Vikings and Muslims further weakened Carolingian power. By the time of Louis's death theempire was in serious decline.