Michael II Komnenos Doukas

Thessalonica had never regained its power after the battle of Klokotnitsa, in which the Bulgarian emperor Ivan Asen II defeated, captured, and later blinded Theodore Komnenos Doukas, the despotēs of Epirus.

His brother Manuel Komnenos Doukas had taken power in Thessalonica, while their nephew Michael II Komnenos Doukas took over Epirus.

Theodore, released in 1237, had overthrown his brother and set up his son John Komnenos Doukas as ruler of Thessalonica.

Michael II's relations with the Empire of Nicaea ensured his neutrality during the conflict in which John III Doukas Vatatzes had conquered Thessalonica and penetrated into northern Greece in 1244.

Theodore's younger son Demetrios Angelos Doukas had lost Thessalonica to Nicaea in 1246 and Michael had allied with the Latins against the Nicaeans.

John III had forced Michael to recognize him as emperor in 1248, however, and officially recognized him in turn as despotēs in Epirus.

…war breaks out in 1257.

Michael is determined to expand his state at Nicaea's expense.

While he is advancing towards Thessalonica, however, King Manfred of Sicily seizes Dyrrhachium and its environs.

Michael, resolved to take Thessalonica, comes to terms with Manfred and sends him his daughter Helena as wife, ceding the lost towns and the island of Corfu as dowry.

Michael also concludes an alliance with Prince William II Villehardouin of Achaea, giving his daughter Anna as a bride.

After the death of Theodore II in August 1258, Michael, his uncle Manuel, and William fight the new Nicaean emperor Michael VIII Palaiologos, defeating a Nicaean army led by George Akropolites and overrunning the Nicaean possessions in Macedonia.

The Venetians retake Chalkis in 1258.

The alliance between Achaea and Epirus is very unstable.

Michael of Epirus has meanwhile set his sights on Thessalonica.

Despite several efforts to reach a diplomatic settlement, the issue between the rival contenders has finally to be resolved in Macedonia on the plain of Pelagonia.

Manfred sends four hundred knights in support of the Epirote and Achaean forces, but the allied operation is compromised by mutual suspicion.

Michael's illegitimate son John Doukas deserts to the enemy and Michael himself abandons his allies while the Nicaeans, led by John Palaiologos, a brother of Emperor Michael VIII Palaiologos, inflicted a crushing defeat on William, who is captured in the battle.

Consequently, while Michael flees to the Ionian islands, …

…much of Epirus comes under Nicaean control, and …

…Villehardouin has to cede to the Nicaeans a number of fortresses, including …

…Maina, …

…Monemvasia, and …

…Mistra.