The long drawn-out divorce action that Lothar ii, a great-grandson of Charlemagne, brought against his wife, Theutberga, in order to free himself to marry his concubine, Waldrada, was a ninth-century cause célèbre. Karl Heidecker sees it, quite rightly, not just as a dynastic scandal, but more importantly as a critical episode in the development of marriage doctrine in the Latin Church. It raised fundamental issues about the legal consequences of marriage, jurisdictional competence in matrimonial law, and the relationship between ecclesiastical and royal power structures. Lothar maintained that Hucbert, Theutberga's brother and one of the most powerful men in his realm, had coerced him to marry Theutberga. Had he failed to comply, Lothar claimed, he feared that he might lose his kingdom. Thus, he argued, their union had been fatally flawed from the outset because he had not freely consented to it. Accounts of the case appear in many contemporary annals and chronicles, but they betray scant sympathy for Lothair's actions. Indeed, they unanimously found Lothar's argument unconvincing and his actions culpable. Modern historians have tended to agree with that assessment. Lothar struck back at contemporary critics by confiscating their property, while he rewarded those willing to support his cause by granting them generous favours. The most tightly-focused and influential contemporary treatment of the whole affair is the treatise De divortio Lotharii regis by Hincmar, archbishop of Reims. Further information about it appears in fifty or so contemporary letters, especially those by Pope Nicholas i, as well as in the proceedings of three councils held at Aachen and another that took place at Metz. The Carolingians were a fractious family and Lothar's divorce embroiled his brothers, King Charles of Provence and the Emperor Louis ii (who was also king of Italy), not to mention his uncles, Louis the German, who reigned in East Francia, and Charles the Bald, king of West Francia, both of whom hoped to divide Lothar's kingdom between them. Heidecker argues that Lothar's divorce action was a critical episode in the development of the medieval matrimonial doctrines that defined marriage as monogamous and indissoluble. His judgement is borne out by the dozen or so references to the case in the Decretum Gratiani. Heidecker chose to cast his account of Lothar's divorce action in the form of a six-act play and certainly it contains enough drama to warrant that unconventional choice. His narrative flows smoothly and his analysis of the whole affair is cogent. Heidecker's work represents a welcome and important contribution to the history of medieval marriage doctrine as well as to the history of the later Carolingian monarchy.