The Mongol conquest of the Song dynasty (or Song–Yuan War) was the final phase of the Mongol conquest of China, beginning under Ögedei Khan (r. 1229–1241) and being completed under Kublai Khan (r. 1260–1294). It is considered the last great military achievement of the Mongol Empire; upon its completion, the Mongols ruled all of continental East Asia under the Han-style Yuan dynasty that had been founded as a division of the Mongol Empire.
Background
Before the Mongol–Jin war escalated, an envoy from the Song dynasty of China arrived at the court of the Mongols, perhaps to negotiate a united offensive against the Jin dynasty, who the Song had previously fought during the Jin–Song wars. While Genghis Khan refused during his life, upon his death in 1227 he bequeathed a plan to attack the Jin capital by passing through Song territory. Subsequently, a Mongol ambassador was killed by the Song governor in uncertain circumstances. Before receiving any explanation, the Mongols marched through Song territory to enter the Jin's redoubt in Henan.
The 1227 incident
In the early spring of 1227, Genghis Khan ordered a small fraction of the army to advance into the Song Lizhou Circuit, in the name of attacking Jin and Western Xia. The five prefectures of Jie, Feng, Chen, He and Tianshui were ravaged. Then the Mongols moved southward and seized Wenzhou. In July, the Mongols returned to the north. Genghis Khan further realized that to destroy the Jin dynasty the Mongol army must make its way via the Song. The 1227 incident (Chinese: 丁亥之變) was the first armed conflict between the Mongols and the Song, but it was incidental to the Mongol conflict with the Jin.
Battles of Shukou
From the winter of 1230 to the autumn of 1231, the Mongols forcibly passed through regions of the Song. In the region centered on the three passes of Shukou (Chinese: 蜀口), they entered into a series of battles with the Song army. This was the second and largest armed conflict between them before the Mongol conquest of Song officially began.
After the conquest of Jin
In 1233, the Song finally became allies with the Mongols, who agreed to share territories south of the Yellow River with the Song. Song general Meng Gong defeated Jin general Wu Xian and directed his troops to besiege Caizhou, to which the last Jin emperor had fled. With the help of the Mongols, the Song armies were finally able to extinguish the Jin that had occupied northern China for more than a century. A year later, the Song generals fielded their armies to occupy the old capitals of the Song. They advanced as far as Kaifeng but were completely repelled by the Mongol garrisons under Tachir, a descendant of Bo'orchu, who was a famed companion of Genghis Khan.
Mongol forces, headed by Genghis's son Ögedei Khan, began a slow, steady invasion of the south. Song resistance was fierce, resulting in a prolonged series of campaigns; however, the primary obstacles to the prosecution of the Mongol campaigns was unfamiliar terrain that was inhospitable to their horses, new diseases, and the need to wage naval battles, a form of warfare completely alien to the masters of the steppe. This combination resulted in one of the most difficult and prolonged wars of the Mongol conquests. The Chinese offered the fiercest resistance among all people that the Mongols fought, and the Mongols required every single advantage they could gain and "every military artifice known at that time" in order to win.
More stubborn resistance was put up by Korea and Song towards the Mongol invasions than the others in Eurasia who were swiftly crushed by the Mongols at a lightning pace. The Mongol force that invaded southern China was far greater than the force they sent to invade the Middle East in 1256.
First stage (1235–1248)
From 1235 on, the Mongol general Köden started to attack the region of Sichuan through the Chengdu plain. The occupation of this region had often been an important step for the conquest of the south. The important city of Xiangyang, the gateway to the Yangtze plain, which was defended by the Song general Cao Youwen, capitulated in 1236. In the east, meanwhile, Song generals like Meng Gong (孟珙) and Du Gao (杜杲) withstood the pressure of the Mongol armies under Kouwen Buhua because the main Mongol forces were at that time moving towards Europe. In Sichuan, governor Yu Jie adopted the plan of the brothers Ran Jin and Ran Pu to fortify important locations in mountainous areas, like Diaoyucheng (modern Hechuan/Sichuan). From this point, Yu Jie was able to hold Sichuan for a further ten years. In 1239, General Meng Gong defeated the Mongols and retook Xiangyang, contesting Sichuan against the Mongols for years. The only permanent gain was Chengdu for the Mongols in 1241. In the Huai River area, the Mongol Empire's commanders remained on the defensive, taking few major Song cities, although Töregene Khatun and Güyük Khan ordered their generals to attack the Song.
Many Han Chinese defected to the Mongols to fight against the Jin. There were 4 Han Chinese tumens, with each tumen consisting of 10,000 troops. The four Han Chinese generals Zhang Rou, Yan Shi, Shi Tianze, and Liu Heima commanded the four Han Chinese tumens under Ögedei Khan.
The conflicts between the Mongols and the Song troops took place in the area of Chengdu. When Töregene Khatun sent her envoys to negotiate peace, the Song imprisoned them. The Mongols invaded Sichuan in 1242. Their commanders ordered Han Chinese tumen general Zhang Rou and Chagaan (Tsagaan) to attack the Song. When they pillaged Song territory, the Song court sent a delegation to negotiate a ceasefire. Chagaan and Zhang Rou returned north after the Mongols accepted the terms.
The Mongols made heavy use of indigenous ethnic minority soldiers in southern China rather than Mongols. The Dali Kingdom's indigenous Cuan-Bo army led by the Duan royal family were the majority of the forces in the Mongol Yuan army sent to attack the Song during battles along the Yangtze River. During a Mongol attack against the Song, there were only 3,000 Mongol cavalry at one point under the Mongol commander Uriyangkhadai, and the majority of his army were native Cuan-Bo with Duan officers.
An account of the Mongol attack on Nanjing was given in a Chinese annal, describing the Chinese defenders' use of gunpowder against the Mongols:
As the Mongols had dug themselves pits under the earth where they were sheltered from missiles, we decided to bind with iron the machines called zhen tian lei [thunder-shaking-the-sky]... and lowered them into the places
where the translation of the term for the device is that of Prof. Partington, who describes it as an iron pot filled with [huo] yao, literally "fire drug", a low-nitrate gunpowder or proto-gunpowder, sometimes lowered on chains, that sent forth "fire... out of every part", with an incendiary effect over many yards that could pierce metal to which it was attached, producing a "noise like thunder" that could be heard for miles, with the result that "the men and the oxhides were all broken into fragments (chieh sui) flying in all directions".
Second stage (1251–1260)
The Mongol attacks on Southern Song intensified with the election of Möngke as the Great Khan in 1251. Passing through the Chengdu Plain in Sichuan, the Mongols conquered the Kingdom of Dali in modern Yunnan in 1253. The Mongols besieged Ho-chiou and lifted the siege very soon in 1254. Möngke's brother Kublai and general Uriyangkhadai pacified Yunnan and Tibet and invaded the Trần dynasty in Vietnam.
Uriyangkhadai led successful campaigns in the southwest of China and pacified tribes in Tibet before turning east towards Dai Viet by 1257. In the autumn of 1257, Uriyangkhadai addressed three letters to Dai Viet emperor Trần Thái Tông demanding passage through southern China. After the three successive envoys were imprisoned in the capital Thang Long (modern-day Hanoi) of Dai Viet, Uriyangkhadai invaded Dai Viet in December 1257 with generals Trechecdu and Aju in the rear. In October 1257, Möngke had set out for South China and fixed his camps near Mount Liupan in May 1258. Möngke entered Sichuan in 1258 with two-thirds of the Mongol strength.
According to the Đại Việt Sử ký toàn thư, Mongol forces under Uriyangkhadai battled the larger Trần army led by emperor Trần in Bình Lệ steppe (Bạch Hạc) on 17 January 1258, northwest of Thăng Long. On 22 January 1258, Uriyangkhadai successfully captured the Dai Viet capital Thang Long (now known as Hanoi). While Chinese source material incorrectly stated that Uriyangkhadai withdrew from Vietnam after nine days due to poor climate, Uriyangkhadai left Thang Long in 1259 to invade the Song dynasty in modern-day Guangxi as part of a coordinated Mongol attack with armies attacking in Sichuan under Möngke Khan and other Mongol armies attacking in modern-day Shandong and Henan. Around 17 November 1259, Kublai Khan received a messenger while besieging Ezhou in Hubei who described Uriyangkhadai's army advances from Thang Long to Tanzhou (modern-day Changsha) in Hunan via Yongzhou (modern-day Nanning) and Guilin in Guangxi. Uriyangkhada's army subsequently fought its way north to rejoin Kublai Khan's army north of the Yangtze river on their way back to northern China. While conducting the war in China at Diaoyu Fortress in modern-day Chongqing, Möngke died, perhaps of dysentery or cholera or from a defender's projectile, near the site of the siege on 11 August 1259.
The central government of the Southern Song meanwhile was unable to cope with the challenge of the Mongols and new peasant uprisings in the region of modern Fujian led by Yan Mengbiao and Hunan. The court of Emperor Lizong was dominated by consort clans, Yan and Jia, and the eunuchs Dong Songchen and Lu Yunsheng. In 1260, Jia Sidao became chancellor who took control over the new emperor Zhao Qi (posthumous title Song Duzong) and expelled his opponents like Wen Tianxiang and Li Fu. Because the financial revenue of the late Southern Song state was very low, Jia Sidao tried to reform the regulations for the merchandise of lands with his state field law.
Gunpowder weapons like the tuhuo gun (突火槍), which fired bullets from bamboo tubes, were deployed by the Chinese against the Mongol forces.
The Tusi chieftains and local tribe leaders and kingdoms in Yunnan, Guizhou and Sichuan submitted to Yuan rule and were allowed to keep their titles. The Han Chinese Yang family ruling the Chiefdom of Bozhou which was recognized by the Song dynasty and Tang dynasty also received recognition by the Mongols in the Yuan dynasty and later by the Ming dynasty. The Luo clan in Shuixi led by Ahua were recognized by the Yuan emperors, as they were by the Song emperors when led by Pugui and Tang emperors when led by Apei. They descended from the Shu Han era king Huoji who helped Zhuge Liang against Meng Huo. They were also recognized by the Ming dynasty.
Prelude and surrender of Song (1260–1276)
After Kublai was elected Great Khan of the Mongols in 1260, he was eventually able to conquer the Song to the south, but at great cost. From 1260 to 1264, he first faced civil insurrection within the Mongol empire, led by his younger brother, Ariq Böke, who had been left in command of the north and stationed at the Mongol capital, Karakorum. This led to the Toluid Civil War and was followed by a major confrontation at the Diaoyu Fortress in Sichuan in 1265. The Mongols eventually defeated the Song land and naval armies and captured more than 100 ships.
The Yuan dynasty created a "Han Army" (漢軍) out of defected Jin troops and an army of defected Song troops called the "Newly Submitted Army" (新附軍). Southern Song Chinese troops who defected and surrendered to the Mongols were granted Korean women as wives by the Mongols, whom the Mongols earlier took during their invasion of Korea as war booty. The many Song Chinese troops who defected to the Mongols were given oxen, clothes and land. As prizes for battlefield victories, lands sectioned off as appanages were handed by the Yuan dynasty to Chinese military officers who defected to the Mongol side. The Yuan gave defecting Song Chinese soldiers juntun, a type of military farmland.