This dissertation examines the prevalence and judicial pursuit of local war, that is wars fought between nobles, prelates, and towns, in southern France from c. 1250 to 1380 in order to understand the relationship between the control of large-scale violence and the growth of royal power at the end of the Middle Ages. It demonstrates that such wars took place with surprising frequency during this period and with little reference to the larger historical forces affecting France at this time. It also describes the manner in which such wars were fought, particularly in comparison to royal wars. Examining the royal response to these wars, it argues that although the crown did issue decrees articulating an ideological position against the seigneurial exercise of warfare, it did not enforce these decrees as if they were universally binding legislation. Scrutiny of royal prosecutions against warmakers shows that the crown's proctors used these decrees instrumentally as one justification among many to Interfere in seigneurial warfare. Furthermore, the crown did not simply initiate prosecution and execute judicial sentences, but rather engaged in an open-ended process of negotiation with warmakers in which the objective seems to have been the settlement of dispute rather than the application of abstract nouns. Yet while the crown was demonstrably not pursuing a coherent program to reserve the use of force to itself at the expense of seigneurial privileges, it did succeed in making a role for itself in these local power struggles. In summary, the dissertation shows that royal authority over local lords was much more limited than is usually thought and suggests that the crown's power grew as much through engagement with the seigneury as from struggle against it.