Möngke is noted as participating in the campaign of 1236-1242. He led a mongol corpse against the Kypchaks and Alans and beheaded their leader Bachman, then destroyed Alani capital Maghas, before sacking italian ports in Crimea in 1239. Mongke was impressed by the splendour of Kiev and demanded their submission in order to save the city. But Kievans, who killed mongol envoy before, refused to surrender again and Mongols . Mongke fought against Hungarians at with Batu. In the summer of 1241, before the premature end of the campaign, Möngke returned home.
After the death of the third Great Khan, Güyük, Möngke found himself the champion of the factions of Genghis' descendants who aimed to supplant the branch of . , the senior male of the family, had almost come to open warfare with Güyük in 1248, the khan's early death precluding this. Batu joined forces with Tolui's widow to outmaneuver the regent, Ögedei's widow Oghul Qaimish. Batu called a kurultai in Siberia in 1250, which was protested as not being in Mongolia proper. However, Batu ignored the opposition, had his brother Berke call a kurultai within Mongolia, and elected Möngke khan in 1251.
Realizing they had been outmaneuvered, the Ögedeiid faction attempted to overthrow Möngke under the pretext of paying him homage, but their conspiracy was clumsy and easily avoided. Oghul Qaimish was sewn up into a sack and drowned.
In 1252 and 1256, He conducted a census all over Mongol Empire including Persia, Russia and North China. There was only uprising in Novgorod against the Mongol rule in 1257, but Alexander Nevsky forced the city to submit to Mongol census and taxation.
Möngke, as khan, seemed to take much more seriously the legacy of world conquest he had inherited than did Güyük. He concerned himself more with the war in China, outflanking the Song Dynasty through the conquest of in 1254 and an invasion of Indochina, which allowed the Mongols to invade from north, west, and south. Taking command personally late in the decade, he captured many of the along the northern front. These actions ultimately rendered the conquest a matter of time. He dispatched his brother Hulagu to the southwest, an act which was to expand the Mongol Empire to the gates of Egypt. European conquest was neglected due to the primacy of the other two theaters, but Möngke's friendliness with Batu ensured the unity of empire.
However, while conducting the war in China at Fishing Town in modern-day Chongqing, Möngke died near the site of the siege on August 11, 1259.
Notes on his death
There are several different accounts as to how he perished. Generally recorded as killed in action by cannon shot from Song Chinese artillery, he's also reported to have been killed by an arrow shot from a Chinese archer during the siege. Other accounts claim that he died of dysentery or even a cholera epidemic. In any case, his death forced Hülegü, along with his top general Guo Kan, Jalayirtai to abort their campaigns in Syria and Korea to engage the tenacious Southern Song, and would ultimately cause a civil war that destroyed the unity and invincibility of the Mongol Empire.
In popular folklore, famous Chinese novelist Jin Yong dramatized the death of Mongke Khan in his famous Condor Trilogy series , which describes a melancholic Southern Song warrior and martial artist by the name Yang Guo as the unwilling hero who fired the shot that killed the great Khan. Nevertheless, Mongke was the only Great Khan to have ever been killed in action.