Battle of Versinikia: The Bulgars led by Krum defeat the Byzantine army near Edirne. Emperor Michael I is forced to abdicate in favor of Leo V the Armenian.
The Battle of Versinikia (Bulgarian: Битката при Версиникия; Greek: Μάχη της Βερσινικίας) was fought in 813 between the Byzantine Empire and the Bulgarian Empire, near the city of Adrianople (Edirne).
Despite being outnumbered 2-to-1, the Bulgarians led by Krum were victorious, resulting in the dethroning of Byzantine leader Michael I Rangabe (811–813) by Leo V the Armenian. The battle was a major success and further strengthened the Bulgarian position after their decisive victory over Nicephorus I two years earlier. In fact, after the battle they de facto took control of the whole of Eastern Thrace (until the Byzantine–Bulgarian Treaty of 815) with the exception of a few castles that remained in Byzantine control. For the first time in Bulgarian history, the way to Constantinople was opened. Unfortunately for them, the great Khan Krum died at the height of the preparation for the final siege of the Byzantine capital on 13 April 814.