The New International Encyclopædia/Byzantium

​BYZANTIUM, bī-zān′shĭ-ŭm (Gk. Βυζάντιον Byzantion). A city which stood on the Thracian Bosporus, at the east end of the Propontis. It was founded about B.C. 600, by Dorian colonists, probably from Megara, and rapidly rose in importance as a seat of commerce. Its position was at once secure and enchanting; it commanded the shores of Europe and Asia, and had magnificent facilities for trade. After a time of subjugation under Darius Hystaspis, Byzantium was occupied by the Spartan general Pausanias. Later the city joined the Delian League, and its importance is shown by its large contributions. At the time of the Samian revolt (B.C. 440), Byzantium seems to have tried to withdraw, but reappears in the tribute lists two years later, and remained loyal to Athens until (B.C. 411, when it joined Sparta. Retaken by Aleibiades B.C. 409), it was again captured by Lysander after the battle of Ægospotami. Spartan tyranny led to a change of feeling, and about B.C. 390 Thrasybulus, the Athenian, re-established the democracy, and before B.C. 378 Byzantium concluded a treaty of alliance with Athens. This friendship was of short duration, and finally, in B.C. 357, Byzantium leagued itself with Chios, Rhodes, and King Mausolus II. of Caria, in the Social War. In B.C. 341–40 Philip of Macedon advanced against the city, and, under the influence of Demosthenes, the citizens once more joined Athens. Under Alexander the Great and his successors, Byzantium retained its independence, but for some years after B.C. 278 was subject to a heavy tribute imposed by the Celts. The duties imposed to meet this burden led to a war with Rhodes, in which the city was supported by Attalus I. of Pergamum. During the Roman wars Byzantium seems to have supported Rome, and, as a result, in spite of some suffering in the Mithridatic wars, enjoyed considerable prosperity. In the civil war between Septimius Severus and Pescennius Niger, Byzantium sided with the latter. It was, therefore, besieged by Severus, and, after a brave defense of three years' duration, was captured in A.D. 196 and reduced to ruins. Severus, repenting the desolation which he had made, rebuilt a part of the city, ornamented it with baths, porticoes, etc., and restored to the inhabitants their ancient privileges. In a.d. 330, after the defeat of Licinius, Constantine made the city the capital of the Roman Empire, under the name of Constantinople (q.v.).