Nicaea, titular see of Bithynia Secunda, situated on Lake Ascanius, in a fertile plain, but very unhealthful in summer. It was first colonized by the Battaei and was called Ancora or Helicora. Destroyed by the Mysians, it was rebuilt about 315 B.C. by Antigonus, after his victory over Eumenius, and was thenceforth called Antigonia. Later Lysimachus enlarged it and called it Nicaea in honor of his wife. At first the kings of Bithynia resided there almost as often as at Nicomedia between which and Nicaea arose a struggle for influence. It was the birthplace of the astronomer Hipparchus and the historian Dio Cassius. Pliny the Younger frequently mentions the city and its public monuments. Numerous coins of Nicaea attest the interest of the emperors. After the first Ecumenical Council, held there in 325, Constantine gave it the title of metropolis, which Valens afterwards withdrew, but which it retained ecclesiastically. In the fifth century it took three suffragans from the jurisdiction of Nicomedia, and later six. In 787 a second Ecumenical Council (the seventh) was held there against the Iconoclasts, which, like the first, assembled more than 300 bishops. Among its archbishops, of whom Le Quien (Oriens Christ., I, 639-56) names forty-six, those worthy of mention are Theognis, the first known bishop, a partisan of Arius at the council of 325; Anastasius, a sixth-century writer; Sts. Peter and Theophanes Graptos, two victims of the Iconoclasts in the ninth century; Ignatius, the biographer of the patriarchs Tarasius and Nicephorus; Gregory Asbestus, former metropolitan of Syracuse and the consecrator of Photius; Eustratius, commentator on Aristotle and polemist under Alexius Comnenus; and Bessarion, afterwards cardinal.
Nicaea grew more important during the Middle Ages. Captured by the Seljukids at an unknown date, perhaps subsequent to the revolt of Melissenus against Nicephorus Botaniates, it was afterwards ceded to the Turks by Alexius Comnenus. In 1096 the troops of Peter the Hermit, having attempted to capture the town, were completely defeated and massacred. In June, 1097, the city was taken, after a memorable siege, by the Crusaders and ceded by them to the Greek Emperor Alexius I. It was retained, but with great difficulty, during the twelfth century. After the capture of Constantinople by the Latins in 1204 Nicaea, restored, fortified, and embellished, became until 1261 the capital of the new Byzantine Empire of the Lascari or Palologi. For nearly sixty years it played a most important part. It was finally captured by the Turkish Sultan Orkhan in 1333, from which time it has formed a part of the Ottoman Empire. Today Nicma is called Isnik. It is a village of 1500 Greek and Turkish inhabitants in the sandjak of Erthogrul and the vilayet of Brusa. The Greek metropolitan resides at Ghemlek, the ancient Chios. The ramparts, several times restored and now in a good state of preservation, are 4841 yards in circumference. There are 238 towers, some of them very ancient. Four ancient gates are well preserved. Among the monuments may be mentioned Yechil-Djami, the Green Mosque, and the church of the Assumption, probably of the ninth century, the mosaics of which are very rich.
S. VAILHE