Originally founded as Trapezus by traders from Miletus (traditionally dated to 756 BC), the city was one of a number (about ten) of Milesian colonies along the shores of the Black Sea. Others include Sinope, Abydos and Cyzicus (in the Dardanelles). Like most colonies of the Hellenistic period the city was a small enclave of Greek life, and not an empire onto its own in the European sense of the word.
It remained a city under the rule of one empire or another for some time, and gained importance under Roman rule in the 1st century AD because it was the nearest port to the Armenian frontier. New roads were constructed from Persia and Mesopotamia under the rule of Vespasian and Hadrian commissioned improvements to the city's harbor. The city was pillaged by the Goths in 258, and, although it was afterwards re-built, Trabzond never regained its former glory.
When Constantinople fell to European armies in 1204 as a result of the Fourth Crusade three smaller Greek "empires" emerged from the wreckage: the Empire of Nicaea, Epirus, and Trebizond. Alexius I, a grandson of Byzantine emperor Andronicus I Comnenus, made Trebizond the seat of an empire, and because of this connection the polity was sometimes referred to as the Comnenan Empire. This line of Trapezuntine Comneni added the title Megas ("Grand") to their name and ruled the empire until its end. Trebizond controlled an area across the southern Black Sea coast, and parts of the Crimean peninsula and Kerch briefly in the thirteenth century.
While the Despotate of Epirus came to an end some sixty years after its birth, and the Nicaean Empire managed to retake Constantinople and extinguish the feeble Latin Empire, only to be conquered in 1453, Trebizond managed to outlive either of these competing polities -- despite the fact, as noticed by a fifteenth century visitor, Pero Tafur, that Trebizond had less than 4000 inhabitants. It was an empire more in title than in action, surviving by playing its rivals against each other, and offering daughters of its rulers or marriage with generous dowries. For example, Manuel III, who had succeeded his father Alexius III as emperor in 1390, had allied himself with Timur Lenk, and benefitted from the Turkish defeat at the Battle of Ankara in 1402. His son Alexius IV married two of his daughters to Cihanshah, khan of the Black Sheep Turkmen, and to Ali Beg, khan of the White Sheep Turkmen; while his eldest daughter Maria became the third wife of the Byzantine Emperor John VIII Palaeologus.
John IV could not help but see his Empire would soon share the same fate as Constantinople. Sultan Murad II of the Ottoman Empire first attempted to take the capital by sea in 1442, but high surf made the landings difficult and the attempt was repulsed. While Mehmed II was away laying siege to Belgrade in 1456, the Ottoman governor of Amaseia attacked Trebizond, and while he was defeated, he took many prisoners and extracted a heavy tribute.
John IV prepared for the eventual assault by forging alliances. He gave his daughter to the son of his brother-in-law, Uzun Husan khan of the White Sheep Turkmen, in return for his promise to defend Trebizond. He also secured promises of help from the Turkish emirs of Sinope and Karamania, and from the king and princes of Georgia. Unfortunately after John's death in 1458, his brother David came to power and misused these alliances. David intrigued with various European powers for help against the Ottomans, speaking of wild schemes that included the conquest of Jerusalem. Mehmed eventually heard of these intrigues, and was further proked to action by David's demand that Murad remit the tribute imposed on his brother. Mehmed's response came in the summer of 1461: he led a sizeable army from Brusa, first to Sinope whose emir quickly surrendered, then south across Armenia and neutralizing Uzun Hasan. Having isolated Trebizond, Mehmed quickly swept down upon it before the inhabitants knew he was coming, and placed it under siege. The city held out for a month before the emperor David finalized his surrender on August 15, 1461.
Early History
The Empire of Trebizond
List of Emperors of Trebizond