The Mongol army, led by Hulagu (also spelled as Hulegu) Khan and the Chinese commander Guo Kan in vice-command, set out for Baghdad in November of 1257. Hulagu marched with what was probably the largest army ever fielded by the Mongols. By order of Mongke Khan, one in ten fighting men in the entire Mongol Empire were gathered for Hulagu's army (Saunders 1971). The attacking army also had a large contingent of Christian forces.