Regime Change in the Despotate of Epirus (1246)

Timeline

1. 1246Thessalonica · MacedoniaJohn III Vatatzes led an army to besiege and capture Thessalonica; Demetrios Komnenos Doukas surrendered, the Empire of Thessalonica ended as an independent polity, and Macedonia's core city fell under Nicaean control.
2. 1246–1247Ioannina · EpirusUnder Nicaean military pressure, Epirus's ruler Michael II acknowledged suzerainty and ceded Macedonia and some coastal territories, transforming Epirus from an expansionist independent despotate into a local despotate constrained by Nicaea.
3. 1246–1250Balkan Peninsula · Balkan PeninsulaThe 1246 shift made Nicaea the dominant force among the Byzantine successor states in the Balkans, further squeezing the influence of the Latin Empire and Bulgaria in southern Macedonia, laying the regional groundwork for Michael VIII's later recovery of Constantinople.