The Battle of Irtysh River (Chinese: 額爾齊斯河之戰) or Battle of Yexi River (Chinese: 曳咥河大戰) was a battle in 657 between Tang Dynasty general Su Dingfang and the Western Turkic Khaganate qaghan Ashina Helu during the Tang campaign against the Western Turks. It was fought along the Irtysh River near the Altai Mountains. Helu's forces, consisting of 100,000 cavalry, were ambushed by Su as Helu chased decoy Tang troops that Su had deployed. Helu was defeated during Su's surprise attack, and lost most of his soldiers. Turkic tribes loyal to Helu surrendered, and the retreating Helu was captured the next day.
|Battle of Irtysh River|
|Part of Tang campaign against the Western Turks|
Former vassals of the Western Turks
|Western Turkic Khaganate|
|Commanders and leaders|
|10,000 Tang and Uyghur troops||100,000 troops|