In records from Bithynia in the year 680, the city of Gordoservon or Gordoserbon (Greek: Γορδόσερβον, Proto-Slavic: *Gordŭ Sĭrbŭ, Serbian: Srbograd, Grad Srba, Гордосервон) was a Byzantine city inhabited by Serbs. The name is derived from the Serbs that resettled in Asia Minor (in ca 649 or 667) by Byzantine Emperor Constans II (641–668), who came from the areas "around the river Vardar". A "Bishop of Gordoservon" named Isidore is mentioned in 680/681, and the fact that this town was an episcopal seat gives ground to the thesis that it had a large Serbian population. The Serbs were recruited in large numbers into the Byzantine army especially under Justinian II in the 680s, until the defection of a 30,000-strong Serbian contingent led to the disastrous loss of the Battle of Sebastopolis in 692/693.
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