Монгольская осада Сянъяна и Фэнчэна (1267–1273)

Battles during Mongol invasion of China (1267–1273)
the battle that took place during the late Eastern Han dynasty
Xiangyang surrendered to the army of the Mongol Empire without resistance in 1236. But the Mongols voluntarily left the city after it was briefly held by them in 1236–38. The twin cities of Xiangyang Fenchang, with walls almost 5 kilometers around and 200,000 people, withstood a Mongol assault in 1257. The Mongolian cavalry were lured in Xiangyang where they were slaughtered by the Song defenders due to the fortress's double layered wall design. When a Mongol contingent entered the entrance of the fortress, the Mongol forces would be slaughtered to the last man, while trapped between four walls. The Mongols lifted the siege of Xiangyang. The sudden death of Möngke Khan forced the imperial army of the Mongol Empire to withdraw from the Song territory in 1259–60. In 1260, Kublai Khan was proclaimed successor to the throne after the death of his brother Möngke, as was his youngest brother Ariq Böke. The succession war between him and Ariq Böke began. Kublai Khan won the war eventually, though his claim as the successor to Möngke was only partially recognized by the Mongols in the west. In 1271, Kublai Khan renamed his empire "Yuan", establishing the Yuan dynasty, instead of "Ikh Mongol Uls" (Great Mongolian Nation or Great Mongol Empire). After defeating his rivals and opponents in Mongolia and Northern China, Kublai Khan also wanted to continue his grandfather Genghis Khan's conquest of China. In 1267, Kublai Khan ordered Aju and the Song defector Liu Zheng to attack Xiangyang and Fencheng. General Lu Zende had levied corruption charges against Liu Zheng, the Luzhou prefect, causing Liu Zheng to defect to the Mongols in 1261

Aju and Liu Zheng arrived in 1268 and blockaded the city with a ring of forts. Liu Zheng had advised the cities be starved from Sichuan by building forts there. The Mongols probed the defenses of Xiangyang and Fancheng. The Yuan Mongols learned from their mistake, and this time brought along with them about a hundred trebuchets. These trebuchets had a shooting range of around 100 metres, and could use projectiles of around 50 kg. During Mongol campaigns against the Jin dynasty, the Mongols used about 5,000 trebuchets, and they were very successful in destroying the Jin fortresses. Lu Wende commanded the Song dynasty's Yangtze and his son in law Fan Wenhu and son Lu Wenhuan commanded Xiangyang. However the twin cities had expected an assault by bombardment and prepared for it. The city moat was expanded to a width of 150 metres, forcing Yuan siege weapons to set up at a distance. In addition to reinforcing their walls with clay, they made netting screens ten centimetres thick and ten metres in length to cover them and dampen projectile impact. As a result, the Yuan siege weapons were both ineffective and inaccurate, and the few shots that did land bounced off the wall harmlessly.

The Mongols then started to block Xiangyang off from the rest of Song. A Yuan fleet of 5,000 ships was established, to stop any Song supplies from the Han river. The Han River was blockaded with five stone platforms capped by arbalests. The Mongol trained 70,000 marines but Song food supplies still held out in 1271. The Yuan also sent forces to go around the fortress, and set up camps at the key roads, to stop Song supplies from land. Eventually, Yuan built their own forts at these key locations. From late 1267 to 1271, Song reinforcements from the south tried, many times, to attack the Mongol positions, in order to supply Xiangyang, but outside of Xiangyang, the Song forces were no match for the Mongolian cavalry. The catalog of useless thrusts continued, the Chinese losing 1,000 in October 1270, 2,000 in August 1271, and most of a 3,000 strong force was destroyed the following month. Once the Yuan forts were completed, the situation became hopeless. As a result, the Song forces inside Xiangyang had to depend on themselves. The Song had stored years of supplies within Xiangyang. However, by 1271, the fortress finally ran low on their supplies. Still, the Song troops chose to hang on. Finally, in 1272, a small Song force of 3,000 men was able to break through the Yuan naval blockade, and supplied Xiangyang from the Han river. The force, led by two men both named Zhang, commanded a hundred paddle wheel boats, travelling by night under the light of lantern fire, was discovered early on by a Mongol commander. When the Song fleet arrived near the cities, they found the Mongol fleet to have spread themselves out along the entire width of the Yangtze with "vessels spread out, filling the entire surface of the river, and there was no gap for them to enter." Another defensive measure the Mongols had taken was the construction of a chain, which stretched across the water. The two fleets engaged in combat and the Song opened fire with fire lances, fire bombs, and crossbows. A large number of men died trying to cut through chains, pull up stakes, and hurl bombs, while Song marines fought hand to hand using large axes, and according to the Mongol record, "on their ships they were up to the ankles in blood." With the rise of dawn, the Song vessels made it to the city walls and the citizens "leapt up a hundred times in joy." This was a major morale boost to the defenders. However, no one could get back out to inform others of the success. The Song officials considered that reinforcement lost and Xiangyang, doomed to fall from the lack of supplies, did not send more Song reinforcements afterwards. The high casualties and low success rates ended the transportation of further supplies. Fancheng, after holding out for years, suddenly fell within a few days. The Yuan Mongol army then turned their attention to Xiangyang. Lu Wenhuan sent a messenger to Emperor Duzong of Song, to request immediate reinforcements. The messenger successfully got by the Yuan forts and reached the emperor. But upon hearing the effectiveness of these new trebuchets, the emperor considered Xiangyang lost and did not send reinforcements. For the next few days, Song soldiers looked to the south for reinforcements, but all they saw were Yuan siege weapons and the Mongols waiting to end their lives. The position of Song forces worsened. In February, Yuan siege weapons began bombarding the city and a shot happened to hit a stone bridge inside. When the stone landed, it made a thunderous noise. Song soldiers went to check the damage, and saw that the stone had sunk a few feet into the solid ground. Yuan bombardment began to collapse the city structures as well as reduce the drum tower and turrets on the city walls. Lu Wenhuan surrendered the city on 14 March 1273; he was made governor of Xiangyang and Fancheng under Yuan rule as part of the terms.

Xiangyang, the strongest fortress of the Song dynasty, had fallen. As a result, Yuan forces were free to conquer the rest of southern China. Everywhere else Yuan went, Song fortresses defected as the defecting Song commander in Xiangyang, Lu Wenhuan, ordered other members of his family commanding Song forces to defect to the Yuan. In 1275, the Song government unsuccessfully attempted to negotiate a truce, but by then it was too late. For the six years that Yuan sieged Xiangyang, Song were unable to regroup and strike back at Yuan with their resources in the south. In fact, they could not even get much reinforcements and supplies to Xiangyang, to support the hard working defense there. The emperor of the Song dynasty abdicated on 4 February 1276. Siege crossbows and firebombs were also deployed on Song ships against Mongol forces, in addition to fire lances. The name of the bombs in Chinese was Zhen tian lei. They were made from cast iron and filled with gunpowder, the Chinese Song forces delivered them to the enemy via trebuchets. Armor made out of iron could be penetrated by pieces of the bomb after the explosion, which had a 50 kilometre noise range.

Since the Yuan employed Muslim engineers for the designing of the counterweight trebuchets, they were designated in Chinese historiography as the "Muslim" trebuchet (hui hui pao). The Chinese scholar Zheng Sixiao (1206–1283) indicates that, "in the case of the largest ones, the wooden framework stood above a hole in the ground". After Aju asked Kublai, the Emperor of the Mongol Empire, the powerful siege machines of the Ilkhanate, Ismail and Al aud Din from Iraq arrived in South China to construct a new type of trebuchet which used explosive shells. These Muslim engineers built mangonels and trebuchets for the siege. Explosive shells had been in use in China for centuries but what was new was the counterweight type of trebuchet as opposed to the torsion type giving greater range and accuracy as it was easier to judge the weight of the counter weight than the torsion generated by repeated windings. The counterweight trebuchet built by the Muslims from Mosul were longer in range, and assisted in destroying Fancheng. Chinese and Muslim engineers operated artillery and siege engines for the Mongol armies. The design was taken from those used by Hulegu to batter down the walls of Baghdad. The Chinese were the first to invent the traction trebuchet, now they faced Muslim designed counterweight trebuchets in the Mongol army. The Chinese responded by building their own counterweight trebuchets, an account from the Chinese said in 1273 "the frontier cities have all fallen. But Muslim trebuchets were constructed with new and ingenious improvements, and different kinds became available, far better than those used before."

The Chinese scholar Zheng Sixiao (1206–1283) indicates that, "in the case of the largest ones, the wooden framework stood above a hole in the ground". Another version is given by Marco Polo in his book Il Milione where he claims having been responsible for teaching the Mongols how to build and use catapults during the siege of Xiangyang. However, the names of the Muslim engineers were given by Muslim sources as Talib and his sons Abubakr, Ibrahim and Muhammad, respectively, by Chinese sources as Ala ud Din and Isma'il. Moreover, it has been claimed the siege had already ended before Marco Polo's arrival in China.

Political infighting among the Song also contributed to the fall of Xiangyang and Fancheng; due to the power of the Lü family, many questioned their allegiance to the Song. The Emperor barred Jia Sidao himself from the command, so Li Tingzhi, an enemy of the Lü family, was appointed commander. Jia permitted the Lü family to ignore Li's orders, resulting in a fractious command. Li was then unable to relieve Xiangyang and Fancheng, managing only temporary resupply during several breaks in the siege.