section_path: History/Byzantine period
section_name: Byzantine period
paragraph_text: Byzantine period
  
  By the 4th century, Nicaea was a large and prosperous city, and a major military and administrative centre. Emperor Constantine the Great convened the First Ecumenical Council there, and the city gave its name to the Nicene Creed. The city remained important in the 4th century, seeing the proclamation of Emperor Valens (364) and the failed rebellion of Procopius (365). During the same period, the See of Nicaea became independent of Nicomedia and was raised to the status of a metropolitan bishopric. However, the city was hit by two major earthquakes in 363 and 368, and coupled with competition from the newly established capital of the Eastern Empire, Constantinople, it began to decline thereafter. Many of its grand civic buildings began to fall into ruin, and had to be restored in the 6th century by Emperor Justinian I, among them the aqueduct built by Hadrian.
  
  The city disappears from sources thereafter and is mentioned again in the early 8th century: in 715, the deposed emperor Anastasios II fled there, and the city successfully resisted attacks by the Umayyad Caliphate in 716 and 727. The city was again damaged by the 740 Constantinople earthquake, served as the base of the rebellion of Artabasdos in 741/2, and served as the meeting-place of the Second Ecumenical Council, which condemned Byzantine Iconoclasm, in 787 (the council probably met in the basilica of Hagia Sophia). Nicaea became the capital of the Opsician Theme in the 8th century and remained a center of administration and trade. A Jewish community is attested in the city in the 10th century. Due to its proximity to Constantinople, the city was contested in the rebellions of the 10th and 11th centuries as a base from which to threaten the capital. It was in the wake of such a rebellion, that of Nikephoros Melissenos, that it fell into the hands of Melissenos' Turkish allies in 1081. The Seljuk Turks made Nicaea the capital of their possessions in Asia Minor until 1097, when it returned to Byzantine control with the aid of the First Crusade after a one month siege.
  
  The 12th century saw a period of relative stability and prosperity at Nicaea. The Komnenian emperors Alexios, John and Manuel campaigned extensively to strengthen the Byzantine presence in Asia Minor. Alexios seems to have repaired the aqueduct after the reconquest and major fortifications were constructed across the region, especially by John and Manuel, which helped to protect the city and its fertile hinterland. There were also several military bases and colonies in the area, for example the one at Rhyndakos in Bithynia, where the emperor John spent a year training his troops in preparation for campaigns in southern Asia Minor.
  
  After the fall of Constantinople to the Fourth Crusade in 1204, and the establishment of the Latin Empire, Nicaea escaped Latin occupation and maintained an autonomous stance. From 1206 on, it became the base of Theodore Laskaris, who in 1208 was crowned emperor there and founded the Empire of Nicaea. The Patriarchate of Constantinople, exiled from Constantinople, also took up residence in the city until the recapture of Constantinople in 1261. Although Nicaea was soon abandoned as the primary residence of the Nicene emperors, who favoured Nymphaion and Magnesia on the Maeander, the period was a lively one in the city's history, with "frequent synods, embassies, and imperial weddings and funerals", while the influx of scholars from other parts of the Eastern Roman world made it a centre of learning as well.
  
  After the restoration of the Byzantine Empire in 1261, the city once again declined in importance. The neglect of the Asian frontier by Michael VIII Palaiologos provoked a major uprising in 1262, and in 1265, panic broke out when rumours circulated of an imminent Mongol attack. Emperor Andronikos II Palaiologos visited the city in 1290 and took care to restore its defences, but Byzantium proved unable to halt the rise of the nascent Ottoman emirate in the region. After Emperor Andronikos III Palaiologos and John Kantakouzenos were defeated at Pelekanon on 11 June 1329, the Byzantine government could no longer defend Nicaea. Nicaea finally surrendered to the Ottomans after a long siege 2 March 1331.