Diarchy? The system of co-rulership in Byzantium at the turn of the 13th - 14th centuries and its impact on the situation in the state

Introduction . The study is dedicated to the system of co-rulership in Byzantium in the early Palaiologan period. Our goal is to determine the role of the Byzantine emperor, the son and co-ruler of his father, the emperor Andronikos II Palaiologos (1282-1328), Michael IX (1294-1320) in the political destabilization of the empire at the turn of the 13th - 14th centuries by identifying the specific nature of power relations in the state at the time under study. Methods . The methodological basis of the study is a systematic approach. The power relations in Byzantium at the turn of the 13th - 14th c. are considered as a system of interconnected elements that perform certain functions in relation to each other and to the system as a whole. The principles of the hermeneutic method allow us to give a holistic interpretation of the sources that form our understanding of the subject under study. Analysis and Results . As a result of the study, we found out that the specific nature of power relations in Byzantium at that time was determined by two circumstances. First, by the institutionalization of the co-rulership that occurred during the reign of the first Palaiologoi. It was mostly due to the publication of the prostagma by Michael VIII (1259-1282) in 1272, an important document, many provisions of which, in our opinion, were fully implemented (and, to some extent, even expanded) during the reign of his son Andronikos II. Second, by the division of managerial functions within the ruling family. While Andronikos II dealt with a whole range of issues related to various state activities (fiscal, socio-economic, administrative, political and legal, foreign policy, etc.), the younger basileus concentrated in his hands mainly the command of the army. The isolated position of Michael IX which consisted in his constant stay outside Constantinople and the presence of significant military contingents under his control provided a certain degree of independence for the younger basileus in his military and political decisions which often contradicted those of his father. At the same time, this separate co-existence of two imperial courts in the state with their own staff of courtiers disrupted the unity within a narrow group of the Byzantine elite, led to its disengagement and the appearance of people who associated with the younger emperor their further acquisition of high ranks and broader powers in Byzantium. After the death of Michael IX (1320) this circumstance will have a significant impact on the outbreak of the civil war in the empire (1321-1328).