Cao Pi's Invasion of Wu

Cao Pi's Invasion of Wu was Cao Pi's first attempt to attack Wu, shortly after taking the throne of Wei. Cao Pi's invasion was a large-scale three pronged attack against Wu.

Background
In 221 A.D. Liu Bei led his forces against Wu to exact vengeance for the death of Guan Yu, the forces would meet at Yiling and the Shu forces would be defeated.

Emperor Cao Pi was hoping Wu forces would pursue Liu Bei into Yi province and thus leaving their own territory weakly defended, thereby Wu would destroy Shu and he would destroy Wu, ending the Three Kingdoms period.

Prior to the battle at Yiling, Sun Quan had "surrendered" to Wei, as he knew Liu Bei would soon seek reprisal for the death of Guan Yu. Emperor Cao Pi not only accepted his surrender and even bestowed upon Sun Quan the title of King of Wu and the Nine Dignities, making him just below Cao Pi in rank. So, ostensibly the two kingdoms were allies and not a danger to one another.

Emperor Cao Pi had even tried to invite Sun Quan's son, Sun Deng to court to enfeoff him with titles. But each time, Sun Quan would make some excuse as to why he couldn't go; usually along the lines of Sun Deng being too young to make the journey or too young to understand the ways of the world. "My son is young in years, and furthermore I have not instructed him sufficiently."

The Battle
With Shu forces severely destroyed by the conflict at Yiling, several of the Wu generals: Xu Sheng, Pan Zhang, Song Qian, etc. memorialise the throne to pursue Liu Bei to White Emperor Castle (Baidi Castle). However, Lu Xun, Zhu Ran and Luo Tong send word that Cao Pi is marshalling his forces and pursuing Liu Bei would be disastrous, saying: "Cao Pi has been assembling his troops on a large scale. Ostensibly he claims that he is helping our State in attacking Liu Bei, but in his heart he cherishes a treacherous design. I have respectfully come to a decision that we should speedily respond with war".

With Sun Quan unwilling to send his son as a hostage and affirm his loyalty to Wei, Cao Pi decides to invade Wu. In the ninth month (Oct. 23 - Nov. 23), Cao Pi dispatches his forces in three armies to attack Wu.

Battle of Dongkou
Cao Pi sends General-in-Chief Who Conquers the East Cao Xiu, General of the Van Zhang Liao and General Who Guards the East Zang Ba to attack Dongkou, a slightly smaller fortress downstream from Ruxu fortress

In Wu, General Who Establishes Might Lu Fan took command of five armies to oppose Cao Xiu.

Cao Xiu was positioned north of the Jiang River and eager for battle. Emperor Cao Pi sent as edict checking Cao Xiu, although sentiment about the court at that time was that Zang Ba was too comfortable in his position and reluctant to attempt the dangerous trip across the River. The Palace Attendant Dong Zhao said: "Zang Ba and others are not only rich but in high positions, hence they look for nothing more from life than to die natural death and keep their emoluments and ranks. How can they be willing to risk throwing themselves into a dangerous place to court uncertain fortune?"

"If Zang Ba and his men do not advance, then Cao Xiu will of himself desist. I fear that even if Your Majesty were to issue an edict commanding him to cross the Jiang, he would have to devise some way to do so and not be able to obey the command immediately."

In the 11th month (11 Dec. 222 A.D. - 19 Jan. 223 A.D.), disaster struck Wu. A heavy storm hit the area. The strong winds sheared the ropes mooring the boats and they were carried to the north bank of the river, right into Cao Xiu's camp. Cao Xiu's men killed or captured some 10,000 men and thousands of Lu Fan's men were drowned in the Jiang River. And many others scattered along the river trying to return to the south of the Jiang river.

Cao Pi immediately tried to capitalise on the disaster and ordered Cao Xiu to advance across the Jiang. Cao Xiu ordered Zang Ba to lead the attack. He took 500 light boats and 10,000 volunteers to attack Xuling.

To compound problems, Sun Lang accidentally set fire to the Wu camp. Sun Lang, a palace guard at the time, thought he could use fire to destroy the Wei fleet but his efforts backfired. Instead of destroying the Wei boats, he set fire to the city walls destroying many Wu supplies and siege weapons.

Despite the repeated disasters, Xu Sheng and Quan Cong arrived with reinforcements, driving the Wei forces out. The Wei general Yin Lu was killed along with hundreds of Wei soldiers.

Sun Quan was furious with Sun Lang's blunder. Sun Quan stripped Sun Lang of all titles and ranks and even the Sun family name, and had him imprisoned for life.

Battle of Ruxu Fortress
Cao Pi sends Commander-in-Chief Cao Ren, Wei's highest ranking commander, against Ruxu Fortress

In Wu, Zhu Huan was assigned to be Commander of Ruxu.

In the second month of 223 A.D. (20 Mar.-17 Apr.), Cao Ren marches with tens of thousands of infantry and cavalry against the fortress at Ruxu, but he first spreads misinformation that he is heading east to attack Xianxi.

Cao Ren's deception works, Zhu Huan takes the bait and sends a detachment of men to reinforce Xianxi. It's not until Cao Ren's forces are near that Zhu Huan realises his mistake and tries to recall the relief force. But by the time Cao Ren's forces arrive, Zhu Huan's men have not returned and the Wu forces at Ruxu only numbered 5,000.

Anxiety in Ruxu was high, so Zhu Huan rallied his forces. He impressed upon his men the value of occupying a defensive position, the land's natural defences and that Cao Ren's long march would leave his men fatigue while the Wu forces were well rested. Then, Zhu Huan quickly tore down his banners and hid his drums to put up a facade of weakness.

Cao Ren arrived at Ruxu and saw it appeared empty. Assuming that his misinformation has worked he dispatched his son Cao Tai to seize Ruxu in his stead. Nearby in the river, a small river islet housed the families of the soldiers of Ruxu. So Cao Ren also sent Chang Diao and Wang Shuang with 5,000 men to capture the river islet. Cao Ren decided to take the remaining 10,000 men and camp at Tuogao (Tuo marsh?) to act as rearguard.

Jiang Ji, Cao Ren's advisor, attempted to dissuade Cao Ren from attacking the island. Jiang Ji noted that Ruxu was well stocked with boats and that the Wu forces were far superior at naval warfare.

Zhu Huan quickly split his forces, dispatched General Yan Gui with the fleet to stop Chang Diao, and personally led the defence against Cao Tai.

As Jiang Ji suspected, attacking the islet proved disastrous. The Wu forces intercept the Wei boats on the Jiang. Chang Diao is slain, Wang Shuang captured (he is later returned to Wei) along with several boats and the number of Wei soldiers killed or drowned numbered over a thousand. Cao Tai abandoned his siege, burnt his own camp and retreated.

Siege of Jiangling
In the ninth month of 222 A.D. (23 Oct.-21 Nov.), Cao Pi sends Great General of the First Army Cao Zhen, General Who Conquers the South Xiahou Shang, General of the Left Zhang He and General of the Right Xu Huang to attack Nan commandery in Jing province. Cao Zhen laid siege to Jiangling in Nan commandery with a force of 30,000.

General Who Conquers the North Zhu Ran had been besieged in Jiangling for four months without respite, so Sun Quan sent Sun Sheng with 10,000 men to relieve Jiangling. Sun Sheng set up his camp on a river islet (Bolizhou, "Hundred Li Islet") outside Jiangling in the middle of the Jiang river and built embankments about his camp in defence.

In the first month of 223 A.D. (18 Feb-Mar. 19), Zhang He led a detachment of troops across the Jiang River attacking Sun Sheng and putting him to flight before encamping on it himself.

In the second month of 223 A.D. (20 Mar.-17 Apr.), hearing of Sun Sheeng's defeat, Sun Quan dispatched General of the Left Zhuge Jin, General Who Pacifies the North Pan Zhang, and General Yang Can to relieve the siege of Jiangling. Zhuge Jin encamped on the bank of the Jiang opposite Xiahou Shang's camp. Zhuge Jin splits his forces, sending some against the islet and leaving the rest stationed on the Jiang river.

Xiahou Shang predicted Zhuge Jin's actions and by night has prepared a counter-attack against the Wu reinforcements. Xiahou Shang secretly moves his forces at night and launched his fleet from both sides of the Jiang, sending 10,000 men against both the islet and the forces on the river. Zhuge Jin's forces are heavily defeated as Xiahou Shang sets fire to both his naval fleet and his main camp.

Now, Jiangling had been under siege for six months and two waves of reinforcements had been turned back by the Wei forces. To make matters worse, there was a sickness within the city which reduced the number of troops under Zhu Ran to only 5,000.

The odds were severely against Wu, they were greatly outnumbered, saw no chance of reinforcements, suffering from disease and running low of supplies. In the sixth month of the siege, Yao Tai, the Magistrate of Jiangling, believing the situation to be hopeless, planned to defect to Wei along with others. Yao Tai was in command of the northern city gate and had begun communication with Wei forces to arrange a coordinated attack. Zhu Ran found out about the plot and quickly executed Yao Tai.

At this time, the waters of the Jiang were fairly shallow; so Xiahou Shang decided the best way to achieve victory was to build a pontoon bridge connecting the islet to both river banks to enable easy transport of supplies and troops. Dong Zhao quickly memorialised the throne, stating that Xiahou Shang's plan was incredibly dangerous. He argued that: trying to move across the bridge would bottleneck their forces; that Wu would continually attack the pontoons in an effort to isolate the forces on the southern bank; that the Jiang could flood at any time destroying the bridges; and that at the very least Wei forces should prioritise their safety at the expensive of victory with such a high-risk gambit. Cao Pi agreed and commanded the undertaking be abandoned.

Pan Zhang had noticed the bridges and had led a contingent of men 50 li (25 km or 15 mi) up river and had cut down reeds to build rafts, which he planned to ignite and send down the Jiang. Pan Zhang was simply waiting for the waters to rise to put his plan in action.

Fortunately for the Wei forces, orders to withdraw came and they retreated from the river islet. As predicted by Dong Zhao, the retreat was painfully slow across the narrow pontoon bridges. Only 10 days after the retreat was called did the waters of the Jiang begin to rise up, so disaster was narrowly diverted and Cao Pi praised Dong Zhao on his foresight.

Eventually the Wei army started to succumb to sickness (possibly contracted from those within the city) and were forced to retreat.