The Kamakura period in Japan (1185-1333) was the first time that aristocratic rule in Kyoto was confronted by a competing warrior power in Kamakura, known as the Kamakura Bakufu. Historians in recent decades have cogently redefined this period as a transitional age between Japan's classical and medieval periods, but in their studies have restricted historical analysis to documentary evidence while rejecting the value of more belletristic texts. This dissertation engages critically with a wider range of source material, including texts often categorized as literature, to investigate cultural and social implications of the Kamakura-period that cannot be gleaned from documents. In particular, my study engages with the history of warrior and courtier relations seen in the lead-up, outbreak, and aftermath of a war known as the Jokyu Disturbance of 1221. In this event, the powerful retired emperor Go-Toba instigated a war against Hojo Yoshitoki, the de facto leader of the newly emergent Kamakura Bakufu. Disastrously defeated within the span of a month, Go-Toba and his sons were all sent into exile by the Bakufu, which emerged from its victory more powerful than before. The shock waves Go-Toba's defeat sent through medieval society reveal the complexity of thirteenth-century Japan, characterized by divided loyalties, overlapping networks of interpersonal ties, and changing perceptions of social identity. By explaining, justifying, or condemning Go-Toba's actions in 1221, medieval writers explored new ways of understanding imperial authority, loyalty and honor, and the roles of court and warrior government, providing deeper insight into early medieval Japanese history.