The First Battle of Marcellae

Following Khan Kormisosh's unsuccessful operations against Byzantium, the emperor decided to campaign against the Bulgarian state, probably then ruled by Khan Vineh. A fleet was sent towards the Danubian lands, while the emperor led the land forces into the interior of Thrace. The battle took place near Marcellae Fortress, close to modern Karnobat in Bulgaria.

The battle ended in a Bulgarian defeat and a victory for Emperor Constantine V.