The Battle of Neopatras was fought in the early 1270s between a Byzantine army besieging the city of Neopatras and the forces of John I Doukas, ruler of Thessaly. The battle was a rout for the Byzantine army, which was caught by surprise and defeated by a much smaller but more disciplined force.
Background
In 1259, the Empire of Nicaea, led by Michael VIII Palaiologos (), had achieved a great victory in the Battle of Pelagonia against a coalition of its major European foes, the Despotate of Epirus, the Kingdom of Sicily, and the Principality of Achaia. This victory had in large measure been achieved through the defection of John Doukas, the illegitimate child of Michael II of Epirus. This victory enabled Palaiologos to consolidate his territories in Europe; further, the weakening of Epirus and the Latin states allowed him to carry out the reconquest of Constantinople in 1261 and to re-establish the Byzantine Empire, with himself as emperor. The Nicaean forces failed however to subdue Epirus: John Doukas quickly returned to his father's allegiance, and the local population remained loyal to Michael II. The Nicaeans were expelled from the area in 1259, and then defeated and driven out from Thessaly as well in 1260.
In 1266 or 1268, Michael II of Epirus died, and his possessions were divided among his sons: his eldest legitimate son, Nikephoros, inherited what remained of Epirus proper, while John, who had married the daughter of a local Vlach ruler of Thessaly, received Thessaly with his capital at Neopatras. Both brothers were hostile to the restored Byzantine Empire, which aimed to reclaim their territories, and maintained close relations with the Latin states in southern Greece. Nevertheless, Michael VIII tried to attach them to him through dynastic marriages: Nikephoros was given his niece Anna Kantakouzene, while one of his nephews, Andronikos Tarchaneiotes, was wed to the daughter of John Doukas, who in addition received the light title of sebastokrator. Michael failed in his aim, however, as both, and particularly John, remained ill-disposed towards him. Following the deeply unpopular Union of the Churches in 1274, the two even provided refuge for the many dissenters and critics of Michael's religious policies.
Nevertheless, through the negotiations, the Act of Union and the submission of the Greek Orthodox Church to the See of Rome, Michael averted the danger of a concerted Latin attack on his state, and was free to move against his enemies. Immediately, he launched offensives against the Sicilian holdings in Albania, and against John Doukas in Thessaly.
The battle
For the campaign against Thessaly (the date is uncertain, most recent scholars favour 1272/3 or 1274/5), Michael assembled a huge force, mostly mercenaries, which contemporary sources put, certainly with considerable exaggeration, at 30,000 (Pachymeres speaks of 40,000 men, including the naval forces). These were placed under his own brother, the despotes John Palaiologos, and the general Alexios Kaballarios. This force was sent against Thessaly, and was to be aided by the Byzantine navy under the protostrator Alexios Doukas Philanthropenos, who was to attack the Latin principalities and prevent them from aiding John Doukas.
Doukas was caught completely by surprise by the rapid advance of the imperial forces, and was bottled up with few men in his capital, Neopatras, which the Byzantines proceeded to lay siege to. Doukas, however, resorted to a ruse: he climbed down the walls of the fortress with a rope and, disguised as a groom, he managed to cross the Byzantine leaguer. After three days, he reached Thebes, where he requested the aid of John I de la Roche (), the Duke of Athens.