Nicaean and Byzantine Suzerainty
Thessalonica never regained its power after the battle of Klokotnitsa. Theodore's younger son Demetrios Angelos Doukas lost Thessalonica to Nicaea in 1246 and Michael II of Epirus allied with the Latins against the Nicaeans. In 1248 John III Doukas Vatatzes of Nicaea forced Michael to recognize him as emperor, and officially recognized him in turn as despotēs in Epirus. Vatatzes' granddaughter Maria later (in 1256) married Michael's son Nikephoros, although she died in 1258. Also in 1248 Michael's daughter Anna married William II, Prince of Achaea, and Michael decided to honour this alliance over his obligations to Vatatzes. The allies were defeated in the ensuing conflict at the Battle of Pelagonia in 1259.
Emperor Theodore II Laskaris allied with Michael II and their children, betrothed by John years before, finally married in 1256, with Theodore receiving Dyrrhachium in return. Michael did not accept this transfer of land and in 1257 revolted, defeating a Nicaean army led by George Acropolites. As Michael marched on Thessalonica, he was attacked by King Manfred of Sicily, who conquered Albania and Corcyra. However, Michael immediately allied with him by marrying his daughter Helena to him. After Theodore II died, Michael, Manuel, and William II fought the new Nicaean emperor Michael VIII Palaiologos. The alliance was very unstable and in 1259 William was captured at the disastrous Battle of Pelagonia. Michael VIII went on to capture Michael II's capital of Arta, leaving Epirus with only Ioannina and Vonitsa. Arta was recovered by 1260 while Michael VIII was occupied against Constantinople.
Read more about this topic: Despotate Of Epirus