The Siege of Trebizond was the successful siege of the city of Trebizond, capital of the Empire of Trebizond, by the Ottomans under Sultan Mehmed II. Mehmed led an army comprising 60,000 cavalry and 80,000 infantry from Brusa in June 1461, first neutralized the allies of Trebizond -- he intimidated the Emir of Sinope into surrendering his domain and person, captured an outpost of Uzun Hassan which discouraged the latter from intervening -- then marched on the city. The Sultan's navy had been blocking the port of the city from resupply for a month before emperor David of Trebizond heeded the advice of logotheteGeorge Amiroutzes and surrendered the city on 15 August 1461. This also brought an end to the Empire of Trebizond.
^Donald M. Nicol, The Last Centuries of Byzantium, 1261-1453, second edition (Cambridge: University Press, 1993), p. 408; Franz Babinger, Mehmed the Conqueror and His Time, translated by Ralph Manheim (Princeton: Bollingen, 1978), pp. 183-197