额尔齐斯河
Su Dingfang defeated Helu's army of 100,000 cavalry at the battle of Irtysh River, fought along the Irtysh River in the Altai Mountains region. Helu had been caught off guard by Su's ambush and suffered a large number of casualties. The qaghan attempted to flee to Tashkent, but was caught the next day and sent to the Tang capital as a prisoner. The remaining tribes of the Western Turks surrendered. Gaozong pardoned Helu, but the qaghan died the following year.