First Bulgarian Empire (9th – 11th c.)
The tensions between the Eastern and Western Churches in the 10th century were taken advantage by Boris I of Bulgaria (852-889). He converted into Orthodox Christianity in exchange for a status of an autonomous archbishopric that was granted by the Patriarchate of Constantinople. However, Simeon I (893-927) proclaimed the Bulgarian Orthodox Church autocephalous and elevated it to the rank of Patriarchate. Simeon’s act disturbed the Byzantines who persuaded the Magyars from Bessarabia to attack Bulgaria. Simeon I managed to repulse the Magyar invasion and severely defeated the Byzantines in the Battle of Bulgarophygon. Simeon decided to destroy the Magyars in Bessarabia and in alliance with the Pechenegs forced the Magyars to move to the Danube area about 899. Afterwards he concentrated on inner politics but his foreign activities were renewed in 913 when he captured Adrianople and advanced towards Constantinople. His campaign against the Byzantine Empire was halted by Romanus I Lecapenus who managed to save the Byzantine Empire from the total disaster. Simeon I namely proclaimed himself Tsar of Bulgaria and Autocrat of the Romans which clearly revealed his aspirations to the Byzantine throne.
The First Bulgarian Empire reached its territorial peak during the reign of Simeon I. He extended the Bulgarian territory over whole eastern Balkan Peninsula to Adrianople and Thessaloniki, and subdued Raska and Epirus. However, the First Bulgarian Empire began to decline under his successor Peter I (927-969), while Boris II (969-971) lost eastern Bulgaria to the Byzantine Empire and was deposed in 971. The western lands remained independent after the Byzantine conquest of eastern Bulgaria and organized a rebellion against the Byzantine Empire. The rebellion was led by the brothers of the Comitopuli dynasty: David, Moses, Aron and Samuil. The latter concentrated all power in his hands after the death of his brothers but he recognized the brother of Boris II, Roman (977-997) who escaped from the Byzantine captivity in 977 as emperor. Samuil remained the chief commander of the Bulgarian army although he was de facto a co-ruler with Roman. Thus Samuil (977-1014) was proclaimed Emperor of Bulgaria when Roman died childless in 977.
Samuil’s rule was characterized by constant warfare with the Byzantine Empire to preserve independence as well as to extend the borders of his empire. The Byzantine Emperor Basil II (also known as the Bulgar-slayer) defeated the Bulgarian forces in the Battle of Belasitsa in 1014, and ordered 14,000 Bulgarian prisoners to be blinded and sent back to Bulgaria. At the sight of his army Samuil supposedly suffered a heart attack and died two days later. He was succeeded by his son Gavril Radomir (1014-1015) who continued his father’s policy and invaded Byzantine territory reaching to Constantinople. He was murdered by his cousin Ivan Vladislav (1015-1018) who assumed the Bulgarian throne with the Byzantine support.
Ivan Vladislav turned against the Byzantine Empire shortly after his accession to the Bulgarian throne. He was killed during the siege of Durazzo in 1018, while most of the Bulgarian territory was subjugated by the Byzantine Empire by 1018. The First Bulgarian Empire came to an end.