This chapter concludes the detailed examination of co-rule with two responsibilities most intimately connected with lordship in medieval thought and modern scholarship: war and justice. During the succession dispute, the Montfortists raised the standard complaint that a woman could not undertake these duties, but the Penthièvre case argued that inheritance and shared power circumvented this objection. Jeanne’s actual engagement with responsibilities of jurisdiction and warfare demonstrates that although her role expanded in Charles’ absence, she continually acted in her own right rather than as a proxy or intercessor, two dynamics strongly linked to women’s exercise of power (and particularly to queenship). This independence allowed Jeanne to use power-sharing as an active strategy to stabilize her and Charles’ position during periods of protracted negotiations, as two case studies show. At the same time, theoretical and practical distinctions made between performing these seigneurial responsibilities in service to one’s lord, and one’s own exercise of lordship, embedded the gender dynamics of spousal co-rule within the negotiation of power across the French sociopolitical structure.

This critical biography of Jeanne establishes a framework for the thematic analyses of subsequent chapters. It outlines Jeanne’s family background, marriage, and motherhood, before detailing the paternal and maternal inheritance which was the basis of her eventual power. It argues that Jeanne’s succession seemed more secure in the lead-up to 1341 than has generally been assumed in light of the war’s outcome. For the period of the war itself, it turns away from the standard military-oriented account to highlight the turning points that most influenced Jeanne’s governance and role. It also examines the neglected final twenty years of Jeanne’s life, including her financial difficulties and her position during the 1379 rebellion, as an important comparison with her official tenure as duchess.

This chapter analyses the complex social position of the duke of Brittany as presented in the legal arguments for Jeanne’s succession in 1341, a document which has been completely overlooked by modern historians. It argues that the debate centred around the ambiguity of the ducal rank: did the duke legally have more in common with the nobles of Brittany than with the kings of France? In this framework there were two communities (to use the modern terminology) or bodies politic (the medieval) to which the duke could conceivably belong and where their primary responsibilities lay. While this was a learned view constructed for immediate advantage, the case reflected wider contemporary difficulties with parsing the internal stratification of the nobility and the inherent tension within the ducal role as a subordinate sovereign. These challenges were exacerbated because standards of divided succession influenced contemporary interpretations of status, overlaying questions of shared lordship over the different hierarchical layers. The blurring of these lines challenges the historiographical prioritization of the competitive centralization of power through the strict demarcation of ruler and ruled in the later Middle Ages.

This chapter is the first of three to treat different aspects of Jeanne’s administration to assess how and why the balance of power could vary within a single ruling partnership. It examines the basic material foundations of lordship: land, inheritance, and money, including a survey of the financial challenges in Jeanne and Charles’ rule. It shows that coordination on significant matters was paired with the ability to act independently and more efficiently on lesser transactions. But these shared concerns did not erase distinctions between Jeanne and Charles’ personal responsibilities and status, which influences our understanding of why spousal co-rule functioned so readily in medieval society. Building on the centrality of inheritance within noble society, the chapter highlights two dynamics that enabled the distribution of power between spouses: the emphasis on lineage among the aristocracy, and the practices of divided succession and co-lordship that were prevalent across France, neither of which has been sufficiently studied in relation to co-ruling couples. By reconciling competing ideals of unitary and multiple lordship, these partible seigneurial standards offer an alternative or supplemental framework for contextualizing such ruling partnerships beyond the delegations of authority stressed in studies of monarchy in this period.

While the defence of princely legitimacy had to respond to certain legal and social standards, this technical reality did not act as a fixed template for its eventual performance. This chapter examines the practical and rhetorical aspects of three components of Jeanne’s legitimacy over the course of her whole career: her status as the rightful heiress of Brittany, her exercise of princely rights and responsibilities, and her responses to the disunity of the duchy. Although Jeanne’s claims were rooted in broadly accepted social expectations, not only could her assertions of legitimacy diverge from those of her husband and her predecessors, but she foregrounded different aspects of her status before different audiences; at the same time, other aspects of her official position remained constant even across the major shifts in her political circumstances. Recognizing princely legitimacy as a moving target expands our understanding of what constituted an effective response to a position of weakness, and tempers the ‘ideal’ prince of medieval (and modern) theory with constructions of power more adaptive to the concurrent pressures of princely relationships and authority.

This chapter assesses the impact of co-rule on the duchess’ political networks, using this external perspective which rarely features in studies of shared power to concretize the contemporary perceptions of joint authority. The stability, composition, and affiliations of two well-documented groups within the administration – the ducal council and the regional officials across Brittany – differentiate Jeanne and Charles’ scope of administration according to both chronological and geographic circumstances. Despite these differences, Jeanne actively worked together with Charles to reward their followers’ loyalty and maintain these political relationships; correspondingly, service to the duchess and duke was largely interchangeable, even for formal relationships such as homage. This relatively level hierarchy further links spousal co-rule to the other power-sharing structures in the medieval aristocracy, which promoted the idea (if not always the practice) of equality between lords.

The historiography of elite women has often contrasted ‘power’, the effective ability to command and be obeyed, with ‘authority’, the sanctioned right to lead. Using Jeanne’s charters as an idealized projection of her actual position, this chapter argues that this model is too restrictive to reflect contemporary understandings of lordly roles. On the surface, these texts seem to associate Jeanne with ‘authority’ and Charles with ‘power’, but a closer examination reveals that neither authority nor power was monolithic: different types of authority coexisted with different types of power, and all could vary jointly or independently. Moreover, these concepts were not static points of reference, but were actively manipulated by contemporaries according to various social norms. This suggests that instead of using the power/authority dichotomy, a more effective model of power dynamics would account for both the people or things over which power was exerted, and the practical and ideological grounds on which it worked. Approaching power from this contextually specific angle enables more diverse comparisons by privileging no single explanatory factor, aim, or outcome of power, and gives greater insight into the complexity of medieval political structures and their social functions.