This thesis aims to reassert the importance of the supranational dynasties of Europe in medieval history by considering the so-called Angevins of Naples, and specifically Charles II (1285-1309), whose matrimonial policies led to the end of the first phase of the Sicilian War and to the peace of Caltabellotta (1302). In particular, the study emphasizes the fact that the Angevins were part of the Capetian French royal house and thus refocusses the role of the Capetians within Christendom at that time, as their previous historiography has concentrated on their role within France. It investigates the the part that the various marriage combinations played in the Sicilian peace process and how they connected with Charles II's internal family strategies, demonstrating how his plans to keep most of the patrimony for his primogenitus was compromised by deals that meant that large parts of the inheritance had to be passed to daughters instead. The following chapter shows how Charles was prepared to relegate other dynastic interests to achieve these deals and how his unbalanced provision for his sons led to conflict within the dynasty. Moving on to a discussion of the legal side of marriage, the thesis discusses how Charles II was able to work within the canon law on consent, consanguinity and divorce to achieve his aims and how far the aristocratic ideas of the Duby model still conflicted with the Church. Taking the discussion of political marriage beyond the marriage treaties themselves, using the extensive correspondence between the Angevins and the royal house of Aragon, it is argued that the importance of dynastic marriage lay as much in the bonds of friendship forged between houses that were the basis of reciprocal duties and favours that were the warp and weft of medieval political life.