page_title: Byzantine–Bulgarian war of 913–927
section_title: Political background
hierarchical_section_title: Byzantine–Bulgarian war of 913–927 / Prelude / Political background
caption_attribution_description: English: Byzantine emperor Leo VI receives a Bulgarian delegation
context_page_description: The Byzantine–Bulgarian war of 913–927 was fought between the Bulgarian Empire and the Byzantine Empire for more than a decade. Although the war was provoked by the Byzantine emperor Alexander's decision to discontinue paying an annual tribute to Bulgaria, the military and ideological initiative was held by Simeon I of Bulgaria, who demanded to be recognized as Tsar and made it clear that he aimed to conquer not only Constantinople but the rest of the Byzantine Empire, as well.
  In 917, the Bulgarian army dealt a crushing defeat to the Byzantines at the Battle of Achelous, resulting in Bulgaria's total military supremacy in the Balkans. The Bulgarians again defeated the Byzantines at Katasyrtai in 917, Pegae in 921 and Constantinople in 922. The Bulgarians also captured the important city of Adrianople in Thrace and seized the capital of the Theme of Hellas, Thebes, deep in southern Greece. Following the disaster at Achelous, Byzantine diplomacy incited the Principality of Serbia to attack Bulgaria from the west, but this assault was easily contained.
context_section_description: In the first years after his accession to the throne in 893, Simeon I successfully defended Bulgaria's commercial interests, acquired territory between the Black Sea and the Strandzha mountains, and imposed an annual tribute on the Byzantine Empire as a result of the Byzantine–Bulgarian war of 894–896. The outcome of the war confirmed Bulgarian domination in the Balkans, but Simeon I knew that he needed to consolidate his political, cultural and ideological base in order to fulfil his ultimate goal of claiming an imperial title for himself and eventually assuming the throne in Constantinople. He implemented an ambitious construction programme in Bulgaria's new capital, Preslav, so that the city would rival the splendour of the Byzantine capital. Simeon I continued the policy of his father Boris I (r. 852–889) of establishing and disseminating Bulgarian culture, turning the country into the literary and spiritual centre of Slavic Europe. The Preslav and literary schools, founded under Boris I, reached their apogee during the reign of his successor. It was at this time that the Cyrillic alphabet was invented, most likely by the Bulgarian scholar Clement of Ohrid.
  The Magyar devastation of the country's north-eastern regions during the War of 894–896 exposed the vulnerability of Bulgaria's borders to foreign intervention under the influence of Byzantine diplomacy. As soon as the peace with Byzantium had been signed, Simeon I sought to secure the Bulgarian positions in the western Balkans. After the death of the Serb prince Mutimir (r. 850–891), several members of the ruling dynasty fought over the throne of the Principality of Serbia until Petar Gojniković established himself as a prince in 892. In 897 Simeon I agreed to recognize Petar and put him under his protection, resulting in a twenty-year period of peace and stability to the west. However, Petar was not content with his subordinate position and sought ways to achieve independence.
  The internal situation of the Byzantine Empire at the beginning of the 10th century was seen by Simeon I as a sign of weakness. There was an attempt to murder emperor Leo VI the Wise (r. 886–912) in 903 and a rebellion of the commander of the Eastern army Andronikos Doukas in 905. The situation further deteriorated as the emperor entered into a feud with the Ecumenical Patriarch Nicholas Mystikos over his fourth marriage, to his mistress Zoe Karbonopsina. In 907, Leo VI had the patriarch deposed.
caption: A Bulgarian delegation and Leo VI, Madrid Skylitzes
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