Byzantine Rule (1018–1185)

The Byzantine conquest of Bulgaria culminated in 1018 under Emperor Basil II, who systematically subdued Bulgarian resistance and incorporated the territory into the empire. Initial resistance hotspots included the northwestern city of Sirmium, where Byzantine commander Constantine Diogenes personally killed the local governor, bringing the city under Byzantine control. Around the same time, a failed Bulgarian revolt was led by Elemag and a figure named Gavra in Belgrade, aiming to restore the Bulgarian state. These last efforts gradually faded, and the entire Bulgarian realm was subdued. Basil II celebrated his victory with a grand procession in Constantinople, symbolically ending the half-century struggle and marking Bulgaria's integration into the Byzantine political and religious order.

The political context of this period was shaped by Byzantine ideology that viewed Bulgaria as a rebellious province rather than a sovereign state. After the fall of the First Bulgarian Empire in 971 and the subsequent wars led by the Komitopuli brothers from 976, the Byzantines regarded any Bulgarian attempts at independence as usurpations or apostasy. Basil II's reign marked a turning point with his moral and political transformation, enabling him to exercise full imperial authority and launch decisive campaigns against Bulgaria. His military strategy focused on vulnerable eastern Bulgarian lands near the Byzantine capital, gradually re-establishing imperial administration and creating a secure base for further advances.

The Bulgarian ruler Samuel had initially managed to unite Bulgarian lands and resist Byzantine advances, reclaiming eastern territories and even launching offensives towards Thessalonica. However, after his death in 1014, his son Gavril Radomir briefly ruled before being succeeded by his cousin Boril, who faced internal challenges from rivals like Alexius Slav and Strez. Despite internal instability, Boril continued anti-Byzantine policies, including warfare against the Latin Empire and the Kingdom of Thessalonica, reflecting ongoing regional tensions.

Following the final Byzantine conquest, the empire reorganized the Bulgarian lands into the theme of Bulgaria, a militarized province governed by strategoi, dukes, or katepans, with the administrative center in Skopje. This theme system reflected Byzantine provincial governance and aimed to integrate Bulgarian territories fully. Over the 11th and 12th centuries, the Byzantine administration faced challenges from local magnates and external threats, including the emergence of the Bogomil heresy originating in Bulgaria during Tsar Peter's reign, which reflected religious and social tensions within the region.

The late 12th century saw the gradual weakening of Byzantine control in the Balkans. Emperor Manuel I Comnenus had restored imperial authority over much of the Balkans by 1172, including Bulgaria and Macedonia, which were divided into themes under military governors. However, local magnates and vassal princes, especially in Serbia, increasingly asserted autonomy. The Serbian lands experienced frequent revolts and dynastic changes, culminating in the rise of Stefan Nemanja around 1166, who established a new ruling dynasty and expanded Serbian power. Nemanja's initial resistance to Byzantine authority eventually gave way to submission and vassalage under Manuel I, illustrating the complex interplay of local and imperial power.

Throughout this period, the Byzantine Empire sought to maintain control through military campaigns, administrative reforms, and symbolic acts of dominance, such as the triumphal entries of emperors into Constantinople with Bulgarian captives and relics. Despite these efforts, the empire faced persistent challenges from Bulgarian resistance, religious dissent, and the ambitions of neighboring states, setting the stage for the eventual re-emergence of Bulgarian independence in the late 12th century.