The Battle of Peritheorion on 7 July 1345 between the forces of Momchil, the quasi-independent ruler of Rhodope, and an allied Byzantine-Turkish force headed by John VI Kantakouzenos and Umur Bey of Aydin. The two armies met in front of the walls of the city of Peritheorion (near Xanthi, now in ruins), and the battle resulted in a crushing victory for the allied army, with Momchil himself falling in the field.