Battle of Xiangyang (1268-1273): The Mongol Siege of the Song

The Battle of Xiangyang was a siege of about five years, from 1268 to 1273, in which the armies of Kublai Khan blockaded and finally captured the Song dynasty’s twin fortress cities of Xiangyang and Fancheng on the Han River. It was the decisive campaign of the Mongol conquest of southern China. The siege is also famous in the history of technology, because it was ended by counterweight trebuchets built by engineers from the Middle East.

Background: the gateway to the Yangtze

By the 1260s the Mongols had ruled northern China for decades, but the Southern Song, ruling from Lin’an (modern Hangzhou), still held the rich lands south of the Huai River and the Yangtze. Earlier attacks, including Möngke’s campaign of 1258-1259, had failed in the rugged west.

In 1267-1268 Kublai, newly secure after the Toluid civil war, accepted the advice of Liu Zheng, a Song general who had defected in 1261, to strike at Xiangyang. Xiangyang lay on the south bank of the Han and Fancheng on the north, joined by a pontoon bridge. Together they controlled the river route from the north China plain to the middle Yangtze.

The Song had learned the value of the cities the hard way. In 1236, during an earlier Mongol war, Xiangyang had fallen when its garrison mutinied, and the Song recovered it only in 1239. Since then they had rebuilt its walls and kept a large garrison there, treating it as the anchor of their defences between Sichuan in the west and the Huai River in the east.

The blockade

Song defences were strong. Xiangyang had thick walls, a wide moat and stores for a long siege, and was commanded by Lü Wenhuan. A direct assault was hopeless, so the Mongol commanders Aju and Liu Zheng built forts and walls around the cities and set out to cut them off.

The defenders had large stores of grain, and they did not starve quickly. Chinese accounts say that the shortage was of other necessities, such as salt, cloth and firewood, and that soldiers tore down buildings for fuel as the years passed.

The key was the river. The Mongols had little naval tradition, so Kublai’s commanders built a large fleet and trained crews of Chinese sailors to stop Song boats from bringing supplies up the Han. The sources give figures of thousands of ships and tens of thousands of trained men, which may be exaggerated but show the scale of the effort.

Relief attempts

The Song court, dominated by the chief minister Jia Sidao, was slow to respond. Later tradition accused Jia of hiding the gravity of the siege from Emperor Duzong, though modern historians think the hostile Song and Yuan histories exaggerated his faults. A relief force under Xia Gui was defeated in 1269, and a larger effort under Fan Wenhu failed in 1271.

In 1272 two officers, Zhang Shun and Zhang Gui, led about 3,000 volunteers in a famous night run upriver with supplies. They broke through the blockade and reached Xiangyang, but Zhang Shun was killed in the fighting. Zhang Gui later tried to break out to fetch help and was captured and killed. These episodes made the defenders heroes in later Chinese memory and in popular fiction, but the city’s position remained desperate.

The counterweight trebuchets

Chinese armies had long used traction trebuchets, worked by teams of men pulling ropes. Kublai asked his nephew Abaqa, ruler of the Ilkhanate in Iran, for experts in a more powerful type. Two engineers, Ismail and Ala al-Din, arrived in 1272.

Counterweight trebuchets had developed in the Mediterranean and the Middle East during the 12th century and were used in the wars between Crusaders and Muslim states. Instead of relying on human pullers, they used a heavy weighted box at the short end of the throwing arm. Released, the falling weight swung the arm with great force and, because the weight was always the same, gave more consistent aim.

Ismail and Ala al-Din built such machines, called “Muslim trebuchets” (Huihui pao) in Chinese, which used a heavy weighted box to swing the arm. The Yuan history says they threw stones weighing about 150 jin, roughly 90 kilograms, which smashed through walls and buildings.

In early 1273 the Mongols stormed Fancheng after cutting the bridge to Xiangyang. Its commander Fan Tianshun took his own life, the general Niu Fu died fighting in the streets, and much of the garrison and population were killed. The trebuchets were then turned on Xiangyang. A stone struck one of the city’s towers with a noise said to be like thunder. With no hope of relief, Lü Wenhuan surrendered in March 1273 and entered Mongol service, and the city was spared a sack.

Key people

• Lü Wenhuan: Song commander of Xiangyang, who held out for about five years before surrendering and later served the Mongols against the Song.
• Aju: Mongol general, son of Uriyangkhadai and grandson of the famous commander Subutai, who led the blockade.
• Liu Zheng: a Song general who defected in 1261 and helped build the Mongol river fleet.
• Jia Sidao: chief minister of the Song, blamed by later historians for failing to relieve the city.
• Ismail and Ala al-Din: Muslim engineers from the Ilkhanate who built the counterweight trebuchets.

Consequences

The fall of Xiangyang opened the way to the Yangtze. In 1274 Kublai appointed Bayan of the Baarin to lead the final campaign. His army, guided in part by former Song officers like Lü Wenhuan, moved down the Han and the Yangtze, defeated Jia Sidao’s army in 1275 and reached Lin’an.

The Song court surrendered in 1276. Loyalists fled south with child emperors, but their last fleet was destroyed at the Battle of Yamen in 1279. Kublai, who had proclaimed the Yuan dynasty in 1271, now ruled all of China.

Myths and facts

• Myth: Marco Polo, his father and his uncle designed the trebuchets. Fact: Polo’s book makes this claim, but the Polos arrived in China around 1275, and both Chinese and Persian sources credit the Muslim engineers.
• Myth: The Mongols took the city by assault. Fact: Fancheng was stormed, but Xiangyang itself surrendered after negotiation, and its commander was well treated.

Timeline

• 1261: Song general Liu Zheng defects to the Mongols.
• 1268: Mongol forces under Aju and Liu Zheng begin the blockade of Xiangyang and Fancheng.
• 1269: A Song relief army is defeated.
• 1271: A further relief effort under Fan Wenhu fails.
• 1272: Zhang Shun and Zhang Gui break through with supplies; both are killed; Muslim engineers arrive.
• 1273, early: Fancheng is stormed.
• 1273, March: Lü Wenhuan surrenders Xiangyang.
• 1276: The Song capital Lin’an surrenders to Bayan.

Why it matters

Xiangyang was the hinge of the Mongol conquest of China. Its long resistance showed the strength of Song defences, while its fall showed how the Mongol Empire could combine Chinese sailors, defectors and Middle Eastern engineers into one war machine. Within six years of the surrender, the Song dynasty was gone.

The siege also showed how far Mongol warfare had changed since the days of Genghis Khan. Victory came not from cavalry charges but from patience, river fleets and engineering, skills the Yuan would later try to use at sea against Japan and Southeast Asia.