Mongke emulated his grandfather’s basic military strategy by first attacking the smaller and weaker areas before moving against the larger target. For Mongke, this meant starting the conquest with a campaign against the adjacent lands of Sichuan to the west and Yunnan to the southwest of the Sung, and then slowly capturing the larger prize in the closing Mongol net. If the Mongols could gain control of these areas, they could attack the Sung from all sides at once. In May 1258, only three months after Hulegu’s sack of Baghdad, Mongke Khan led his army across the Yellow River. Within a year, they had covered the territory from the cold Onon on the Siberian border to the humid and warm south.
After quickly subduing the outlying kingdoms, Mongke began to move against the Sung dynasty itself during the second year of the campaign, but the weather became extremely hot. The climate differed greatly from anything Mongke, and most of his warriors, had experienced in Mongolia or on their European campaigns. Many of the Mongols suffered from bloody diarrhea, probably dysentery, and then other plagues. Mongke Khan became ill but improved—and then, on August 11, 1259, he suddenly died. Every chronicle lists a different cause of death. The Chinese reported that he died of cholera, the Persians that he died of dysentery, and others claimed he died from a battle arrow. The death of Mongke Khan congealed the empire; advancement ceased.
Rather than racing back home to participate in the selection of a new Great Khan as the Mongol leaders had done after the death of the three previous Great Khans, each faction moved to protect the territory it already held. In the Middle East, the newly triumphant Hulegu occupied the richest lands and cities of the empire; he controlled more wealth than the rest of the Mongol Empire combined. He had already taken some of the prized Azerbaijan pastures of his cousins who ruled Russia. For fear of losing yet more land to him, his cousins held their territory and refused to return to Mongolia for an election. Neither Hulegu in the Middle East nor the Golden Horde, as Jochi’s descendants in Russia eventually became known, wanted to risk losing what territory they already controlled in order to haggle over the supreme title of Grand Khan in Mongolia.
The Mongol Empire reached its greatest extent under Mongke Khan, who was the last of Genghis Khan’s descendants to be acknowledged and accepted as Great Khan by the whole of the Mongol Empire. Many khans would continue to rule over the various parts of the empire, and of them, many would claim to be the rightful heirs to Genghis Khan and to the title of Great Khan. But no one of them would be recognized by all the other factions and lineages. Mongke Khan began, but never finished, the Second Mongol World War. It ended with neither victory nor defeat; it merely flickered out.
His brothers pursued episodic campaigns, but they concentrated efforts on each other more than on outside enemies. Khubilai suddenly turned his attention away from the Sung to challenge the youngest brother, Arik Boke, who ruled Mongolia from Karakorum. Each of them summoned a separate khuriltai in his own territory. The choice between the two contestants, and more importantly between their supporters, seemed sharp and clear. As the better educated, Khubilai had been given lands in the agricultural areas where Chinese culture reigned supreme, and he never inspired the full confidence or approval of other members of the Golden Family. Khubilai preferred buildings and cities. He seemed as comfortable in a palace as in a tent, and he may have even spoken some Chinese. This deviance from the traditional Mongol life contributed to an alien aura that always seemed to engulf him.
In contrast to Khubilai’s cosmopolitan persona, Arik Boke lived very much as a man of the steppes, the Mongol who seldom strayed far from his horse. As the youngest son, he was the family Otchigen, Prince of the Hearth, like his father, and he could make the same claim of rights over the office of Great Khan that Mongke had made when he posthumously elevated their father to that rank. In addition, Arik Boke inspired confidence from the other members of the Golden Family by posing less of a threat to their control of their own lands, while Khubilai’s more imperial style invited suspicion. In keeping with Mongol law, Arik Boke held his khuriltai in the homeland of Mongolia. Mongke Khan’s widow and sons supported him as the legitimate and best heir, as did most other members of the family aside from his two brothers, Hulegu and Khubilai. In June 1260, representatives of all the family branches proclaimed Arik Boke as the Great Khan at the khuriltai in Karakorum.
But Khubilai succeeded in pulling off a coup d’état. Following the advice of his Chinese ministers, Khubilai summoned his khuriltai in his own territory. Aside from his followers hardly anyone came, but the small assembly nevertheless proclaimed him Great Khan. In order to win the loyalty of his Chinese subjects, he additionally proclaimed himself emperor in the same year, 1260, and he chose the title of Zhongtong (Chung-t’ung), meaning “central rule.” This title was a Chinese adaptation of the Mongolian designation of the Great Khan as the Central camp and his armies as the Left and Right.
No matter how untraditional his selection may have been by Mongol standards, Khubilai exercised strong control over the Chinese army as well as his own detachment of Mongols; more important, he controlled the flow of food that Karakorum needed to survive. The population of the Mongol steppe city had swollen too much to survive on the local herds alone, and the land around Karakorum, despite sustained efforts to encourage foreign farmers, proved inhospitable to agriculture. Without substantial and continual food shipments from the farmlands controlled by Khubilai, Karakorum had to be evacuated or face starvation.
Khubilai cut off the food and then sent his army to capture Karakorum. Arik Boke fought hard but withdrew steadily against the overwhelming size of his brother’s Chinese army. Karakorum fell quickly to Khubilai, but in 1261 Arik Boke temporarily took it again. The armies of the dueling khans met two more times, but gradually Arik Boke Khan’s army weakened and began to atrophy as it faced desertions of allies who saw that the younger khan would never prevail against his older, better-equipped, and probably more intelligent elder brother. Arik Boke also faced the worst threat to the Mongols: zud, or animal famine. From 1250 to 1270, Mongolia suffered a lowering of temperatures. In a fragile ecological zone such as Mongolia, a change of only a few degrees in annual temperature severely reduces the small amount of precipitation, restricts the growth of the grass, and thereby weakens or kills the animals. Without strong horses or ample food, the supporters of Arik Boke, already cut off from the agricultural largesse of Khubilai Khan’s territory, proved too weak to mount a sustained war. The winter of 1263 proved particularly cruel, and by the following spring, Arik Boke no longer had a viable power base. Unable to feed his followers, Arik Boke proceeded to Shangdu, where he surrendered to Khubilai in 1264.
When the brothers met at the end of the protracted struggle, Khubilai forced Arik Boke to perform a public ceremony of obeisance. Before the assembled court, Khubilai interrogated his brother, demanding to know which of the two sides in the struggle for the office of Great Khan was the correct one. Arik Boke’s answer showed the strength of his pride even in the face of defeat. “We were then, and you are today.” Other members of the family, including the distant brother, Hulegu, reacted so bitterly to Khubilai’s public shaming of his younger brother that they complained to him. Khubilai summoned another khuriltai on Mongolian territory to decide the fate of Arik Boke and to ratify himself as the legitimate khan without the taint of his earlier election on Chinese soil. Despite the overwhelming military might of Khubilai’s army, the Golden Family refused to attend. They recognized the reality of Khubilai’s rule, but none of them proved willing to participate in a criminal trial of Arik Boke, whom they had supported as Great Khan. None of them trusted Khubilai enough to take the chance of leaving their homelands and perhaps never returning. In the absence of a quorum for a khuriltai, Khubilai forgave his brother. Khubilai tried and executed many of his brother’s supporters, but his only punishment of Arik Boke, at least publicly, was banning him from court. Shortly thereafter, in 1266, mysteriously but conveniently for Khubilai, Arik Boke, still in the prime of life, suddenly sickened and died. He had almost certainly been poisoned.