Nicomedia

Nicomedia, the modern İzmit in Turkey, was founded as a Megarian colony in 712–711 BC under the name Astacus, meaning "lobster." After Lysimachus destroyed that settlement, Nicomedes I of Bithynia rebuilt it in 264 BC, renaming it Nicomedia. The city became the capital of the Roman province of Bithynia and is frequently mentioned in Pliny the Younger’s letters to Emperor Trajan, which describe its public buildings—including a senate-house, aqueduct, forum, and temple of Cybele—as well as a devastating fire. The great general Hannibal Barca spent his final years in Nicomedia and died by suicide in nearby Libyssa. The historian Arrian was born there. A third-century Jewish tomb inscription from the city, decorated with a menorah, shofar, and Sukkot symbols, attests to a Jewish diaspora community that included a "reader" of Hebrew scriptures.

In 286 AD, Emperor Diocletian made Nicomedia the eastern and most senior capital of the Roman Empire under the Tetrarchy system. The city was central to the Diocletianic Persecution of Christians: on 23 February 303, Diocletian ordered the razing of its newly built church, the burning of its scriptures, and the seizure of its treasures, followed by the First Edict Against the Christians. Two fires then damaged Diocletian’s palace; his Caesar Galerius blamed Christians and oversaw multiple executions. The Tetrarchy ended in 324 when Constantine the Great defeated Licinius at the Battle of Chrysopolis. Constantine used Nicomedia as his interim capital for six years before dedicating nearby Byzantium as Constantinople in 330. He died in a royal villa near Nicomedia in 337. A major earthquake and subsequent fire in 358 devastated the city, which was rebuilt on a smaller scale. Under Justinian I, new public buildings were added. Nicomedia remained a key military center for Byzantine campaigns against the Caliphate and later served as a base for Alexios I Komnenos against the Seljuk Turks, hosting both the First and Second Crusades. The local bishopric became a metropolitan see in 451. The city was briefly held by the Latin Empire after Constantinople’s fall, was taken by the Ottoman sultan Orhan Gazi, retaken by Byzantines after the Battle of Ankara, and definitively fell to the Ottomans in 1419.