The city was also involved in the Byzantine civil war of 1341–1347: in 1342 John VI Kantakouzenos besieged Peritheorion in vain, where his domestic opponents were staying. Also in the following year he failed to capture, now supported by the allied Emir Umur of Aydın. On July 7, 1345, John V and Umur won a decisive victory over the robber baron Momchil, who had established a quasi-independent rule in the Rhodope Mountains in the battle of Peritheorion in front of the city walls. However, the townspeople did not take part in the clashes and waited for the outcome. In 1355 John Asanes, governor of Peritheorion, handed the city over to Emperor John V Palaiologos, the opponent of John VI. It wasn't until 1357 that John V actually got control of the place.