The Battle of Adrianople

After his victory at Varbitsa Pass and territorial expansion westwards, Khan Krum also turned his attention to the south-east. Adrianople was an important strategic fortress obstructing control of those territories. On 22 June 813, the Byzantine army was defeated near Versinikia Fortress. Historical sources state that Krum left his brother to besiege Adrianople while continuing towards Constantinople himself. Although negotiations had been arranged with Emperor Leo V the Armenian, a plot against Krum prevented them from taking place. Returning from Constantinople towards Bulgaria, he devastated numerous fortresses in Eastern Thrace.

The campaign against Constantinople achieved no major success, but on his return Krum transferred around ten thousand inhabitants of Edirne north of the Danube and established a Bulgarian military administration in Adrianople.