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 Seventh 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" (C. Foss). 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.