Telets leads a well-trained and well-armed army against the Empire and devastates the Empire's frontier zone, inviting the emperor to a contest of strength.

Emperor Constantine V marched north on June 16, 763, while another army is carried by a fleet of eight hundred ships (each carrying infantry and twelve horsemen) with the intent to create a pincer movement from the north.

Telets at first fortifies the mountain passes with his troops and some twenty thousand Slavic auxiliaries.

Later he changes his mind and leads out his troops to the plain of Anchialos (Pomorie) on June 30.

The bloody battle of Anchialus begins at mid-morning and lasts until dusk.

At the end, Telets is deserted by his Slavic auxiliaries, who desert to the emperor, who wins the field, but chooses to return home in triumph.

According to the Byzantine sources, Constantine V brought home a throng of Bulgarian prisoners in wooden restraints, for the entertainment of Constantinople's populace, then had them killed.