Koyulhisar

Koyulhisar guarded a route through the Kelkit valley towards the Black Sea hinterland. In the mid-fifteenth century its fortress became a point of contention between the Ottomans and Uzun Hasan's Aq Qoyunlu, whose interests were tied to the survival of Trebizond. Around 1459 Uzun Hasan's forces took the stronghold; Ottoman attempts to recover it brought siege and plunder to the surrounding country.

In 1460 the struggle also drew food supplies from the Sivas district into Koyulhisar, showing how a frontier castle depended on resources beyond its walls. Diplomacy temporarily accompanied the fighting, but Mehmed II's campaign of 1461 brought the fortress under Ottoman control as he advanced towards Trebizond. Its importance lay in this connection between inland approaches and the coastal kingdom. Koyulhisar was one of the fortified places through which Ottoman and Aq Qoyunlu power confronted each other before the fall of Trebizond changed northern Anatolia's political geography.