The Battle at Demetrias in the Thessalian Campaign of John Palaiologos: A Military Historical Reconstruction

Introduction. The author proposes a new reconstruction of the military-political conditions for the organization of the Thessalian campaign of John Palaiologos, as well as the major naval battle in the history of the Late Byzantine Empire that took place during it. The warfare between the Latin and Byzantine fleets at Demetrias is of interest due to the possibility of battle practice analysis in the context of the formation of the early Palaiologian military-strategic concept and the development of late Byzantine military art in general. Methods. The methodological basis of the work is the critical use of elements of systemic approaches. It should be noted that the system approach allows us to reveal the role and level of mutual influence of political and socio-economic factors that determined the specifics of military organisation and the development of military science and battle practice. Analysis and results. After the renewal of the church union discussion, hoping for the support of Clement IV in the war of the anti-imperial forces, the Byzantines organized a new large-scale campaign in Thessaly. In the spring of 1273, the army of many thousands was sent there. An analysis of the sources that reported detachments about the second stage of the campaign showed that along with the decision to send the French knights to Neopatras, the Lombard barons of Euboea began to form a flotilla. The purpose of the squadron being formed was to inflict a crushing defeat on Byzantium at sea. The reconstruction of the battle at Demetrias showed that the Byzantines were not prepared for the naval battle that had begun. This was due to the fact that the fleet under the command of Philanthropenos, within the framework of the Thessalian campaign, only an auxiliary role was assigned. It could equally act as a cover for the land forces from potential assistance from the Euboean barons and also be used to reshuffle a large land contingent to the area of the main warfare. The analysis of the naval battle showed that the Byzantine army’s military successes were based not only on the talent of the commanders who commanded the military troops during the period of the military organization degradation. In such a significant battle, the defeat of which the entire imperial fleet was threatened with destruction, Philanthropenos’s squadron won thanks to professional training and combat experience, which was based on knowledge of Byzantine polemology. The outcome of the battle was influ