The Battle of Devina

In 1277, a popular uprising led by Ivaylo broke out in north-eastern Bulgaria against Tsar Konstantin Asen and the Tatar invaders. Emperor Michael VIII Palaiologos saw an opportunity to exploit Bulgaria's internal divisions. He sent troops to support his son-in-law and ally Ivan Asen's claim to the Bulgarian throne. In 1279, the Byzantines captured a considerable part of Bulgaria between Vidin and Cherven. Ivaylo was besieged in Drastar, while Tarnovo's notables recognised Ivan Asen as tsar and admitted him to the capital.

After the defeat at Devina, Michael Palaiologos sent another army to support Ivan Asen III, but Ivaylo defeated it too before it crossed the Balkan Mountains. Left isolated in Bulgaria, Ivan Asen fled Tarnovo for Constantinople. Bulgaria's internal struggles ended in defeat for Ivaylo and victory for George Terter.