The Battle of Anchialus took place near the city on 20 August 917, and was one of Tsar Simeon the Great's greatest military achievements. Simeon's army routed the considerably larger Byzantine forces under Leo Phocas. Bulgaria retained the city until 971, when the Byzantine Empire reconquered it and held it for two centuries as Bulgaria was subjugated. After the restoration of the Bulgarian state Anchialos changed hands several times until it was captured by the Venetian knights of Amadeus VI, Count of Savoy in October 1366. The next year it was ceded to Byzantium.