The Byzantines reached the Anchialus fortress and set their camp there unaware of the fact that the Bulgarian army was in the vicinity. While the invaders were gathering food, Tervel and his cavalry charged the outermost Byzantine troops. In the same time the infantry attacked the camp. The Byzantines were surprised and confused; most of them perished in the battle or were captured as well as many horses and arms. The emperor was one of the very few who managed to reach the fortress and escaped to Constantinople on a ship.
The Bulgarians secured the new territorial gains for centuries. In 711 when a riot forced Justinian II to seek for help, Tervel gave him only 3,000 soldiers who after several skirmishes were given safe conduct to Bulgaria by the new emperor and Justinian II was executed.