In 833 emperor Louis the Pious, Charlemagne's son, submitted to a public penance in the wake of a rebellion by his three elder sons. This penance amounted to a deposition, for Louis was to atone for his sins for the rest of his life. However, only half a year later, he was back on the throne again. In this evaluation of Louis' reign, Mayke de Jong argues that his penance was the outcome of a political discourse and practice in which the accountability of the Frankish ruler to God played an increasingly central role. However heated their debates, this was a moral high ground Louis shared with churchmen and secular magnates. Through a profound re-reading of texts by contemporary authors who reflected on legitimate authority in times of crisis, this book reveals a world in which political crime was defined as sin, and royal authority was enhanced by atonement.