The army, except for the Armenians who were then considering an alliance with (or submission to) the Mongols, assembled at Sivas. Kaykhusrev and his allies set out to the east along the trunk road towards Erzurum. On 26 June 1243, they met the Mongols at the pass at Köse Dağ, between Erzincan and Gümüşhane. A feigned retreat by the Mongol horsemen disorganized the Seljuqs, and Kaykhusrev’s army was routed. The sultan collected his treasury and harem at Tokat and fled to Ankara. The Mongols seized Sivas, sacked Kayseri, but failed to move on Konya, the capital of the sultanate.