Battle of Köse Dağ
1243 CE.
Shown on the map at 40.282°, 39.595°.
The Battle of Köse Dağ took place in eastern Anatolia on 26 June 1243 when an army of the Sultanate of Rum, led by Sultan Kaykhusraw II, confronted an invading Mongol army under the general Baiju and was decisively defeated. The battle was the pivotal event of the Mongol conquest of Anatolia: Rum, previously a significant independent power in the eastern Mediterranean, was reduced to the status of a client kingdom, and its territories were later absorbed into the Mongol Ilkhanate. The Mongol Empire first achieved territorial contact with Rum in the early 1230s by conquering a large swathe of western Iran, but largely left it alone over the next decade. Instead, under their general Chormaqan, Mongol armies subjugated Transcaucasia and reduced the Kingdom of Georgia to a vassal state. Relations deteriorated after the accession of Kaykhusraw II to the Rum throne in 1237, and Mongol raids on Rum territory began in 1240. Two years later, Baiju, who had replaced Chormaqan after the latter became disabled, captured and pillaged the city of Erzurum, escalating hostilities into open war.
Text from the Wikipedia article Battle of Köse Dağ, licensed CC BY-SA 4.0.