Louis I, also known as Louis the Pious, was a Frankish king who ruled from 814 to 840 AD. He was the son of Charlemagne and became the Emperor of the Carolingian Empire after his father's death. Louis is known for his attempts to maintain and consolidate the vast empire, which included parts of modern-day France, Germany, and Italy. During his reign, Louis faced challenges such as internal conflicts and divisions among his three sons. His efforts to divide the empire among them led to civil wars, weakening the unity of the empire. Louis I's reign marked a significant period in the history of medieval Europe.