flared again and ultimately led to the deposition in 1328 of Emperor Andronikos II, who retired to a monastery. Reign Military history Ottoman Turks besieged Nicaea in Asia Minor, historically the provisional capital of the Byzantine Empire from the Fourth Crusade until the Byzantine recapture of Constantinople. Andronikos III launched a relief attempt, which Ottoman sultan Orhan defeated at the Battle of Pelekanon on 10 or 15 June 1329. Also in 1329, Andronikos III sent a naval expedition against Martino Zaccaria, Genoese ruler of the Lordship of Chios (which also included Samos and Cos). The expedition deposed Zaccaria, and regained Byzantine control of the islands. An alliance with Bulgaria failed to secure any gains for the Byzantine empire. On 28 July 1330, the Serbians decisively defeated the Bulgarians in the Battle of Velbazhd (modern Kyustendil, Bulgaria) without significant Byzantine participation. The Ottomans continued to advance in 1331, finally taking Nicaea (İznik). Andronikos III wanted Nicomedia and the other few Byzantine forts in Anatolia not to suffer the same fate and sought to pay off the Ottomans with tribute. Andronikos III reorganized and attempted to strengthen the weakened Byzantine navy, which comprised only 10 ships by 1332; in emergencies, he still could muster a hundred extra merchant ships. Having failed to gain anything against Serbia, Andronikos III attempted to annex Bulgarian Thrace, but the new tsar Ivan Alexander of Bulgaria defeated Byzantine forces at the Battle of Rusokastro on 18 July 1332. Andronikos III secured peace with Bulgaria by territorial concessions and the marriage of his daughter Maria (renamed Irene) to Ivan Alexander's son, the future Michael Asen IV of Bulgaria. The Muslim traveler Ibn Battuta visited Constantinople towards the end of 1332 and mentions meeting Andronikos III in his memoirs. Byzantine sources do not attest to the meeting. Stephen Gabrielopoulos, ruler over Thessaly, died circa 1333; taking advantage of the secession crisis, Andronikos III extended Byzantine control over the region. Syrgiannes Palaiologos, entrusted with the governorship of Thessalonica, deserted to the side of king Stephen Uroš IV Dušan of Serbia and aided their advance in Macedonia. He led the Serbians to take Kastoria, Ohrid, Prilep, Strumica, and possibly Edessa circa 1334 and advanced as far as Thessalonica. Byzantine general Sphrantzes Palaiologos, posing as a deserter, entered the Serbian camp and killed Syrgiannes Palaiologos, ending his advance and bringing the Serbian army into disarray. In August 1334, the king of Serbia