The text cites the results of the study of the role of merarches, which were a part of the military organization of the Empire in the early Byzantine period. Later historical documents do not give any notion of this position for more than two centuries. The merarches became a part of the thematic organization in the middle of 9th century. Our ability to fully understand the nature of their function is limited due to the scarcity of source materials; this, however, may be overcome by taking into account, the general and political situation in the Empire, that is, by considering the military reforms executed in the 9th and 10th century. This paper focuses on the problem of the military-administrative competences of the merarches, which have been the subject of different interpretations in the modern, scholarly literature. One of the aims of this research is the definition of the timeframe within which the reestablishment of this rank in the Byzantine army occured. [Projekat Ministarstva nauke Republike Srbije, br. 177032: Tradicija, inovacija i identitet u vizantijskom svetu]
