worsened for Michael. The Arsenite party found widespread support amongst the discontented in the Anatolian provinces, and Michael responded there with similar viciousness: according to Vryonis, "These elements were either removed from the armies or else, alienated, they deserted to the Turks". Another attempt to clear the encroaching Turkmen from the Meaender valley in 1278 found limited success, but Antioch on the Maeander was irretrievably lost as were Tralles and Nyssa four years later. On 1 May 1277, John the Bastard convoked a synod at Neopatras that anathematized the Emperor, Patriarch, and Pope as heretics. In response, a synod was convoked at the Hagia Sophia on 16 July where both Nikephoros and John were anathematized in return. John called a final synod at Neopatras in December 1277, where an anti-unionist council of eight bishops, a few abbots, and one hundred monks, again anathematized the Emperor, Patriarch, and Pope. Michael's achievements on the battlefield were more positive, although still mixed. He tried to take advantage of a civil war in Bulgaria in the late 1270s, but the Byzantine armies suffered several major defeats at the hands of the peasant Emperor Ivaylo. The Emperor managed to temporarily impose his son-in-law Ivan Asen III on the Bulgarian throne, but after the Byzantine defeat at Devina he had to flee. However, Michael VIII later managed to conquer the Bulgarian portion of Thrace, while the internal situation of the Bulgarian Empire remained unstable. In 1275, Michael VIII sent an army against Thessaly and fleet of 73 ships to harass the Latin states in Greece. The army was crushingly defeated at the Battle of Neopatras, but the fleet won a similarly comprehensive victory at the Battle of Demetrias. Last was his victory over Charles of Anjou in western Greece. Charles' general Hugh of Sully with 8,000 men (including 2,000 cavalry) captured Butrinto in 1280 and besieged Berat. A Byzantine army of relief under Michael Tarchaneiotes arrived in March 1281: Hugh of Sully was ambushed and captured, and his army put to flight. Geanaklopos considers that most scholars do not appreciate fully the importance of this victory: "this victory marked the complete failure of the attempt to launch a land expedition against the capital. Thus ... Charles had to shift his strategy to a sea attack against Constantinople". Sicilian Vespers On 22 February 1281 a new Pope was selected, Pope Martin IV, a Frenchman Geanaklopos describes as