<研究ノート>「簒奪皇帝」の栄光と失敗 : ビザンツ皇帝バシレイオス一世の政治運営をめぐって

Abstract

Byzantine Emperor Basil I (r. 867-886), who had usurped the Imperial throne by murdering the former emperor Michael III (842-867) and the Kaisar (Caesar) Bardas (Michael III's uncle), did not have a firm base to operate effectively in the political sphere. Basil I was thus forced to depend on the army, which had supported him before his accession as co-emperor in 866. Of course, Basil was not satisfied with this situation and attempted to establish a close relationship with high-ranking officials (Senators) by choosing a new, loyal staff. Basil's efforts were not successful, and he could not overlook opposition to his rule toward the end of his reign. Basil suppressed their actions violently, and expelled his son and co-emperor Leon (VI) from the throne in 883, claiming that Leon was the leader of the opposition. Although many scholars have argued that Patriarch Photios plotted Leon's downfall, it was actually accomplished under the leadership of Basil I. It has generally been thought that Photios also plotted against Basil I. However this claim is also incorrect. It was unlikely that Photios would have plotted against Basil I, because his position and political influence depended on the support of Basil I. Although Basil I's position was stabilized by these actions, the situation was ephemeral. Tensions between Basil I and high-ranking officials continued, and in the last years of his reign most units of the army stationed in Constantinople (Tagmata) also opposed the emperor; thus, Basil I lost his most credible political base. As a result, the Senate and army took a defiant attitude toward him, and he was forced to reinstate Leon as a co-emperor in 886. We can perceive from this course of events that it was necessary for Byzantine emperors to build intimate relationships and consult both high-ranking officials and the army in order to manage politics effectively. It has been assumed that the Byzantine Empire (especially during 9th-10th century) had a centralized political system in which emperor, who stood atop the hierarchy, exercised despotic and unrestrained power. Indeed, Byzantine emperors occasionally took despotic action, as did Basil I in 883. However, the case of Basil I also shows that there were distinct limitations on the "despotic" power of Byzantine emperors. When the relationship between emperor and influential figures grew precarious, challenges to the emperor were manifest in the form of advice or plots. Basil I also encountered a plot in the spring of 886, and was pressed to reinstate Leon due to the exhortation of Senators and especially Stylianos Zautzes, Basil's reliable subordinate and Hetaireiarches (Commander of Imperial Bodyguards). Although Byzantine emperors could exercise the supreme power within the Byzantine political mechanism, emperors could not disregard the intentions of other powerful members of this mechanism in managing the affairs of state.