page_title: Boril of Bulgaria
section_title: War with the Latins
hierarchical_section_title: Boril of Bulgaria / Reign / War with the Latins
caption_attribution_description: English: Bulgaria under Boril (1207 — 1218) Български: България при цар Борил (1207 — 1218) Based on map "Възстановяване и издигане на Българската държава (1185 — 1241)." in atlas "Атлас по история на България за средните училища", "Картография", София, 1990 г.
context_page_description: Boril was the emperor of Bulgaria from 1207 to 1218. He was the son of an unnamed sister of his predecessor, Kaloyan and Kaloyan's brothers, Peter II and Ivan Asen I, who had restored the independent Bulgarian state. After Kaloyan died unexpectedly in October 1207, Boril married his widow, a Cuman princess and seized the throne. His cousin, Ivan Asen, fled from Bulgaria, enabling Boril to strengthen his position. His other kinsmen, Strez and Alexius Slav, refused to acknowledge him as the lawful monarch. Strez took possession of the land between the Struma and Vardar rivers with the support of Stefan Nemanjić of Serbia. Alexius Slav secured his rule in the Rhodope Mountains with the assistance of Henry, the Latin Emperor of Constantinople.
  Boril launched unsuccessful military campaigns against the Latin Empire and the Kingdom of Thessalonica during the first years of his reign. He convoked the synod of the Bulgarian Church in early 1211. At the assembly, the bishops condemned the Bogomils for heresy. After an uprising broke out against him in Vidin between 1211 and 1214, he sought the assistance of Andrew II of Hungary, who sent reinforcements to suppress the rebellion.
context_section_description: In the reign of Kaloyan, the Greek noblemen of eastern Thrace had risen up against the Bulgarian Empire, seeking assistance from the Latin Empire; this rebellion would continue against Boril, who left for Thrace to reconquer the region in May 1208. Boril left for Thrace to reconquer the region in May 1208. During his march, he seized parts of Alexius Slav's territory before stopping at Stara Zagora. The Latin Emperor personally led his army against Boril, forcing him to withdraw to Plovdiv. Although Boril's army outnumbered the Latin troops, Henry defeated him near the town on 8 July. The Latins captured Plovdiv and Alexius Slav voluntarily paid homage to Henry to secure his assistance against Boril. While Boril was waging war against the Latins, Stefan Nemanjić invaded Macedonia and occupied the land between the Struma and Vardar rivers. He granted the occupied territories to Strez but left Serbian troops in the region to secure his loyalty.
  The Greeks of Serres in the Kingdom of Thessalonica sent envoys to Boril's commander in Melnik, seeking his assistance against the Latins in early 1209. Henry soon intervened and suppressed their revolt. Boril concluded an alliance with Theodore I Laskaris, Emperor of Nicaea, and Michael I Komnenos Doukas, the Greek ruler of Epirus, against the Latins. He also made peace with Strez who had turned against Nemanjić.
  Boril convened a synod of the Church of his realm in Tarnovo in early 1211. The bishops confirmed the Orthodox confession adopted at the synod of Constantinople in 843 and condemned the Bogomils, ordering their persecution as heretics. The synod established the date of Easter in accordance with the Catholic calendar. Boril, who had presided over the synod, ordered the publication of its decisions in Bulgarian on 11 February 1211.
  Boril sent an army to a mountain pass to prepare an ambush for the Latin Emperor Henry who was returning from Thessaloniki to Constantinople in April 1211. Having been informed of Boril's plan, Henry gathered his troops from the nearby Latin fortresses and forced Boril to withdraw his army. Strez invaded the Kingdom of Thessalonica, but Michael of Epirus, who had made peace with the Latins, invaded his realm. Boril intervened in the conflict on Strez's behalf, but their united armies were defeated near Bitola in early summer. He launched an assault on Thessaloniki in October, but Eustace of Flanders, who administered the kingdom as regent, forced him to lift the siege. Alexius Slav intervened the conflict on Eustace's behalf and captured Melnik.
caption: Bulgaria under Boril (1207-1218)
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