From Moesia, the Bulgarians launched attacks in northern Thrace while the Byzantine army was fighting with the Normans, who had attacked Byzantine possessions in the Western Balkans and sacked Salonica, the Empire's second largest city. The Byzantines reacted in mid-1186, when Isaac II organized a campaign to crush the rebellion before it spread further. The Bulgarians had secured the passes but the Byzantine army found its way across the mountains due to a solar eclipse.

The Byzantines successfully attacked the rebels, many of whom fled north of the Danube, making contact with the Cumans. In a symbolic gesture, Isaac II entered Peter's house and took the icon of Saint Demetrius, thus regaining the saint's favour. Still under threat of ambush from the hills, Isaac returned hastily to Constantinople to celebrate his victory. Thus, when the armies of Bulgarians and the Vlachs returned, reinforced with their Cuman allies, they found the region undefended and regained not only their old territory but the whole of Moesia, a considerable step towards the establishment of a new Bulgarian state.