In order to distract the Bulgarian attention from Macedonia, the Byzantine emperor Constantine VI started a campaign in northern Thrace in April 791.

The armies met near the fortress of Provat (20 km east of Odrin) and the Byzantines were forced to retreat, but their defeat was not decisive and in the following year the campaign was renewed.

[2] In the summer of the next year Constantine VI led his army north and on 20 July was confronted by the Bulgarians under Kardam near the border castle Marcellae.

[3][4] Before the beginning of the battle, while awaiting the Byzantine assault, the Bulgarian ruler secretly placed part of his cavalry behind the hills surrounding the battlefield.

Bulgaria entered the 9th century consolidated, stronger and united which was an important factor for the string of victories scored by Krum against the Byzantines.