The second Carolingian emperor, Louis the Pious (814–40), is one of medieval history's great losers. Notwithstanding the tough hand that he was dealt by having Charlemagne as his opening act, posterity has declared itself particularly unimpressed with Louis's handling of dynastic politics, which led to him being deposed not once but twice in the first half of the 830s. Pious, arrogant and weak, he has been seen as everything that his father was not, and the public penance enforced on him by rebellious bishops in 833 has been identified as the moment when Carolingian power was definitively subordinated to the theocratic rule of the Church. Yet, as Mayke De Jong demonstrates in this important and subtle examination of the reign, the traditional model is predicated on dichotomies between the interests of bishops and kings, and between the rulership styles of Charlemagne and Louis, which may never have existed.

Though a detailed narrative is provided in chapter i, the book is not a comprehensive political study of the reign so much as a forensic examination of contemporary narratives dealing with the ‘years of crisis’, 829–35. The central argument is that the conflicts of the reign were played out within an increasingly coherent discourse, originating in the time of Charlemagne, that defined rulership as the shared ministry of the powerful and encouraged a ‘redefinition of political crime as sin’ (p. 246). The antidote to political crisis was therefore collective soul-searching and the energetic appeasement of God, the ultimate expression of which was penance – authority and atonement were two sides of the same coin. De Jong, working up from the vocabulary and citations deployed by contemporary writers, makes an extremely persuasive case that the sources are absolutely soaked in this discourse, which was shared by all the main players, rulers, bishops and lay nobles alike. The emperor expected his advice to come in the form of criticism, as long as it did not go beyond the sorts of criticism that he might reasonably be expected to apply to himself. Indeed, ‘admonitions’ penned by the likes of Agobard, Einhard and Wala can be seen as attempts to gain favour at court: the timing, manner and tone of such criticism was all-important. The 829 Council of Paris, which with its striking citation of texts by Pope Gelasius and ‘Pseudo-Cyprian’ is often taken as a direct statement of the bishops' simmering discontent with Louis as pagans attacked the frontiers and portents filled the skies, transforms in De Jong's reading into a communal session of episcopal-imperial self-recrimination in the face of an angry deity. In this context even the 833 penance that heralded the emperor's deposition seems less like the Stalinist show-trial of yore than an extreme but internally consistent expression of the serious penitential priorities that had been developing since the middle of Charlemagne's reign. The sources are not transparent windows onto primal struggles between ‘Church’ and ‘State’ – an anachronistic distinction in a world where ‘empire’ and ‘ecclesia’ could be used synonymously – but expressions of vigorous rhetorical competition for a moral high ground between members of the ruling class. Whether or not we think that Louis was a loser, De Jong shows that we have not fully understood the rules of the game that he was playing.

De Jong's deft and original evocation of this world of open criticism does not flatten into a description of organic consensus: she makes it clear that admonition could easily escalate into shaming rebuke, and that when this resonated with wider political conflicts (as it did after 830) then ‘the penitential state’ could go ‘spinning out of control’ (p. 213). Yet as convincing as her interpretations of the ways that contemporaries thought and wrote about politics are, De Jong is much less concerned with the political causes of conflict and the motivations of the protagonists. The shifting patterns of patronage, the formation and exclusion of factions and the sharp-elbowed competition for influence that helped to shape the course of all Carolingian reigns are here, but generally glimpsed only in passing; likewise the offended honour, the ready anger and the sheer viciousness of the early medieval elite. The full reassessments of Louis's reign which will no doubt follow the publication of his charters will need to reintegrate these aspects of contemporary politics; but any such reassessment will have to be worked out within the new interpretive framework for the sources staked out in De Jong's outstanding book.