| unknown|| 10 Aug 1230 – 12 Aug 1230|
| Decisive Seljuk and Ayyubid victory|
Battle of Köse Dağ, Battle of Myriokephalon, Battle of Dandanaqan, Battle of Otlukbeli, Battle of Sırp Sındığı
Battle of Yassi Chemen (Turkish: Yassıçemen Savaşı) was a battle fought in Erzincan Province, Turkey in 1230.
Battle of Yassıçemen Wikipedia
Jalal ad-Din was the last ruler of the Khwarezm Shahs. Actually the territory of the sultanate had been annexed by Mongol Empire during the reign of Jalal ad-Din’s father. But Jalal ad-Din continued to fight with a small army. In 1225 he retreated to Azerbaijan and founded a principality around Maragheh. Although initially he formed an alliance with the Seljuk Sultanate of Rûm against the Mongols, for reasons unknown he later changed his mind and began hostilities to Seljuks. In 1230 he conquered Ahlat, (in what is now Bitlis Province, Turkey) an important cultural city of the era from Ayyubids which led to an alliance between the Seljuks and Ayyubids. Jalal ad-Din on the other hand allied himself with Jahan Shah, the rebellious Seljuk governor of Erzurum.
The battle took place in Yassıçemen a location west of Erzincan. Jalal ad-Din tried to attack before the merging of Seljuk and Ayyubid armies. But it was too late. Ayyubids had already sent a reinforcement of 10,000 to Seljuks. The commander of the Seljuk-Ayyubid army was the Seljuk sultan Alaaddin Keykubat I. The battle continued for three days. An able commander, Jalal ad-Din almost defeated Seljuk-Ayyubid alliance in the first day. But at the end of the three days Jalal ad-Din’s forces were defeated.
This battle was Jalal ad-Din’s last battle. He lost his army. While escaping in disguise he was spotted and killed in 1231. His short lived principality was conquered by the Mongols. After the death of Alaattin Keykubat, Seljuks shared the same fate in 1243.