Middle East and Europe
He served Subutai in the conquest of Europe a few years following the fall of the Jin dynasty. He then served in Hulagu's conquest of the Middle East, playing a major role in the capture and battle of Baghdad, devising the strategy of using the dikes to drown the Caliph's army, and supervising the reduction of Baghdad's walls.[3] He was then appointed the first Ilkhanate Governor of Baghdad by Hulagu.[4]
According to the History of Yuan, he was present in the siege of Maymun-Diz during Hulegu's campaign against the Nizaris. Guo Kan attacked the inaccessible fortress by "catapults on mounts" (jiapao).[5]
China
Guo Kan took part in the final drive in the conquest of the Jin dynasty, including the capture of Kaifeng. He then helped Subutai conquer West Eurasia, Europe, and the Middle East and was appointed governor of Baghdad by Hulagu. At some point after Khubilai Khan's accession as Khan, Guo Kan assisted Khubilai Khan in the conquest of the Southern Song and ultimately the unification of China under the Yuan dynasty.[2] By this point the Mongol Yuan empire was nearly fully complete, stretching from China across Central Asia, Siberia, and the Middle East to Europe.
After Guo Kan returned to China with Hulagu Khan following Möngke Khan's death, Guo Kan helped Kublai Khan in the difficult conquest of Southern Song dynasty of Southern China. Khubilai's accession as becoming Khan allowed him to select the best Yuan Generals to serve him. Subutai and Jebe both died of old age, and Guo Kan was the last of the 'Gods of War', so the new Great Khan Khubilai assigned Guo Kan to command the final Yuan expedition and reunification of China.[6][page needed]
Guo Kan reportedly urged Khubilai to adopt a Han Chinese-style dynastic title, establish a capital and central government, and build schools. He reportedly was the general who proposed capturing Xiangyang as a strategy for invading the Southern Song. In 1262, he defeated Song forces in a battle at Xuzhou, and in 1266 urged Khubilai to establish military farms in Huaibei to provide supplies for an invasion of the Southern Song.[1] In 1268 and 1270 he suppressed local rebellions, and then he was sent to participate in the siege of Xiangyang. In 1276, the Song dynasty fell (except for the loyalist movement that lasted until 1279), and Guo served as a prefect for one more year before dying.
Guo Kan was a general who helped unify the massive Yuan Mongol empire. He played an important role in their conquests of all corners of the empire, from the east to west.