Kublai implemented the "new policy" in three regions, with great results and very popular with the hearts of the people of the Central Plains, but it inevitably infringed on the interests of the nobles who were accustomed to seeking arbitrarily. In 1256, he built the palace in the upper reaches of the Luanhe River. The growing power of the vassal states will inevitably arouse suspicion of Mengge . Some nobles and ministers continue to slander, saying that "the royal family has won the hearts of sergeants" and "the royal family members are abusing their power and are profitable" (referring to losing their wealth to the royal family). In this way, the conflict between Mengge and Kublai Khan on the policies and rights and interests of the Han area finally broke out.
1257, Mongge sent Dabizhachi (left prime minister) Alan Daer and Liu Taiping to Shaanxi and Henan to "hook" Qiangu to review and persecute officials of both departments. In fact, it was to crack down on the forces of the Kublai Khan's vassal state and force Kublai to hand over the power of the three regions of Xingzhou , Henan and Shaanxi, and to abolish the three departments. At the same time, Mengge decided to personally lead the troops to conquer the Song Dynasty, and lifted Kublai Khan's military power, allowing him to "rest at home and recuperate." He also sent the sect king Tachaer to lead the left wing to attack Jinghu and Lianghuai, and to lead the right wing army to attack Sichuan, and stayed behind Helin with his younger brother Alibuge .
1 In April of 258, Mengge stationed in Xia Liupanshan ; in July, he divided his troops into Shu, attacked Bazhu Pass ( Longqing Prefecture HTML ), and Eding Fort, and successively captured Changning Mountain City, Dahucheng (Langzhou), Yunshancheng (Pengzhou), Qingju City ( Shunqing Prefecture HTML ), Daliang City (Quzhou) and Bazhou. The former capital of Sichuan, Nurin, defeated the attack on Chengdu by the commander of the Sichuan in Song Dynasty, and took advantage of the victory to capture the city of Yunding Mountain; after Mengge entered Sichuan, he left Milihuozhe, Liu Heima, defending Chengdu, led his army to attack Xuzhou, defeated the Song defenders, broke through the defense line of the Mahu River, and went down the river downstream of Chongqing, blocking the river surface to block the army that aided Sichuan. In early 1259, the Mongolian Ge army entered Hezhou and sent envoys to Diaoyu City to surrender, but was killed by the guard general Wang Jian . Mengge's army entered Diaoyu City, and Wang Jian led the army and the people to resist the defense. The Mongolian army failed to attack for more than five months, and the soldiers were damaged and the generals were lost. In July, Mengge died of illness and the Mongolian army withdrew the circumference and returned to the north.
The left-wing army led by Tachaer attacked Fancheng in the autumn of 1257, but failed and retreated. In the past year, apart from four plunders, a city was not acquired and no military achievements were made. In November of the following year, Mengge had to order Kublai Khan to lead the left-wing army to attack Song. While Kublai Khan was idle, he discussed major plans with his advisers every day and waited for the time to move. After receiving the order to leave the army, he happily moved south from Kaiping. In the spring of 1259, he met the kings in Xingzhou to receive military power. But he was not in a hurry to advance, and first summoned famous scholars such as Song Zizhen, Shang Ting, Li Chang, and Du Ying to visit political gains and losses and plans to attack Song. In July, he went to Runan and sent the general Ba Dulu to go first; he ordered the army to prevent the generals from killing them or burning them to plunder. He ordered Yang Weizhong, , , Hao Jing, , etc. to pacify the Jianghuai River and send officials to supervise the food and fodder.
In August, news that Mengge died in Hezhou came. Kublai Khan decided to continue his troops, crossing the Huai River to the south, and there was no major resistance along the way. He arrived in Huangpi and was in the battle by the river.
In early September, Brother Mo sent envoys from Hezhou to the army to report the news of Mengge's death and asked to return north. Kublai Khan did not want to return without success, and personally directed the troops to cross the Yangtze River from near Yangluobao and stationed in Huhuangzhou, Nan'an. Over the past few days, they entered the siege of Ezhou . The defenders Zhang Sheng and Gundam resisted bravely. Lv Wende led reinforcements from Chongqing to the east, broke into the city, and Ezhou's defense became stronger; Jia Sidao used the prime minister to control all the troops and horses to aid Hubei, and unified command and defense. The Mongolian army sieges for nearly two months and cannot be defeated. The army was short of food and the disease was ill.
In November, Kublai Khan sent envoys to the army and reported that Alibuge had sent trusted ministers to recruit soldiers from the north and south of the desert, and used Tulichi as the official to conduct the affairs of the Secretariat in Yanjing. He had an attempt to seize the throne of Khan, so he asked Kublai to return quickly. At this time, Jia Sidao, the Right Prime Minister of Song and Privy Councilor who led the army to help Hubei, did not dare to launch a counterattack when Kublai Khan was in trouble. Instead, he sent envoys to seek peace, hoping to cut the river into the boundary, and offered 200,000 silver and silk each year (two or two).
Kublai followed the trend and retreated to the north, leaving Badulu to lead a part of the army stationed in Jiangbei. The Wulianghe Taiwan Army, who was ordered to join Yunnan and the north, arrived in , Tanzhou, (Changsha) in November. Xiang Shibi, the commander of the Hunan commander of the Song Dynasty, held on to the ground and could not be defeated for a long time. When Kublai Khan withdrew his troops to return to the north, he sent troops to support Wulianghe's Taiwan troops and then crossed the river to retreat north. The Mongolian war to attack Song came to an end.
History says that Mengge was "strong and wise, strong and resolute, decisive and taciturn, not happy to drink, and not extravagant." "Whenever there is an imperial edict, he must draft it himself, and count it four more and then implement it." "I ordered Jiujiao to collect the seals, inspect the posts, send envoys to investigate the labor taxes, and investigate the taxes, and the people have been corrupt. The defiled officials were abusing officials, and the blame was almost everywhere. He was also eager to govern." However, he adhered to the old Mongolian system and was unwilling to make changes. The main officials appointed to manage the Han area were still corrupt. Due to the conflict of interests with Kublai Khan, the reforms in several effective places were abolished, resulting in the failure of the governance situation in the Han area. His long-term besiege of Hezhou and his lack of knowledge of changing his strategy was also a major military mistake.
Mengge was in charge of Hudutai, and his eldest son was turtled and his youngest son Yulong was missed; his concubine gave birth to a son, Asuda, Xiliji, , Biandu.
