Battle of Didao

Infobox Military Conflict
conflict=Battle of Didao
partof= of the Three Kingdoms


caption=
date=July, 255 to September 25, 255
place=Western China
casus=
territory=
result=Cao Wei pyrrhic victory
combatant1=Cao Wei
combatant2=Shu Han
commander1=Chen Tai,
Deng Ai,
Sima Fu,
Wang Jing
commander2=Jiang Wei,
Xiahou Ba,
Zhang Yi
strength1=Up to 100,000
strength2=At least 30,000
casualties1=At least 30,000
casualties2=Low

The Battle of Didao (狄道之战), also known as the Battle of the Gu Pass (故关之战) and Battle on the Western Bank of Tao River (洮西之战), is a battle in 255 during the Three Kingdoms period in China. It was fought between Shu Han and Cao Wei and resulted in a Cao Wei pyrrhic victory.

Prelude

In July, 255, Jiang Wei decided to take advantage of the death of the regent of Cao Wei, Senior General (大将军) Sima Shi by launching another campaign against Cao Wei. The invasion force was one of the largest Jiang Wei had gathered in his northern expeditions, totalling at least 30,000 men, and they included Shu Han commanders such as Xiahou Ba and Zhang Yi. It was worthy to note that Xiahou Ba and Zhang Yi both held higher ranks than Jiang Wei when performing civic administrative duties, but Jiang Wei was in command instead because it was a military campaign. Xiahou Ba was a blood relative of the Shu Han imperial family (he was an uncle of Liu Shan, the Shu Han emperor, and both of Xiahou Ba’s nieces were married to Liu Shan), and Zhang Yi had seniority over both for joining Liu Bei long before both Xiahou Ba and Jiang Wei. By August, 255, Jiang Wei’s army took Baohan (枹罕, located to the northeast of modern day Linxia), and continued toward Didao City (狄道城, modern day Lintao).

The newly appointed Cao Wei Inspector (刺史) of Yong (雍) province, Wang Jing (王經), immediately notified his direct superior, General Subduing the West (征西将军) of Cao Wei, Chen Tai, claiming that the enemy appeared to attack simultaneously in three fronts, targeting Qi (祁) Mountain, Shiying (石营), and Jincheng (金城, modern day Lanzhou). Wang Jing suggested to his direct superior that the Cao Wei force should face the enemy in three fronts also. Wang Jing volunteered to lead his force to check enemy’s advance toward Shiying, and another Cao Wei force would check the enemy’s advance toward Qi Mountain. Meanwhile, Cao Wei troops of Liang (凉) province should be deployed to Baohan to check the enemy’s advance toward Jincheng. Chen Tai was extremely dubious about this initial intelligence because it was highly unlikely that Shu Han could gather such huge force for the campaign Wang Jing perceived. Nonetheless, the invasion force was one of the largest, and the defending Cao Wei force could not afford to split its forces. Furthermore, Cao Wei troops of Liang province would not be fully utilized if they were deployed elsewhere because they would be fighting in the region they were unfamiliar with. Chen Tai therefore replied to Wang Jing that they must carefully analyze Jiang Wei’s move further because it was unlikely that the invading enemy could afford to split its forces in different fronts, and Cao Wei forces must concentrate their forces to achieve absolute numerical superiority over the enemy. Therefore, Wang Jing must wait until the arrival of reinforcement and avoid engaging the enemy, so Wang Jing was ordered to concentrate his force to guard Didao City for other reinforcement forces, while Chen Tai would lead the reinforcement toward Chencang (陈仓, located to the east of modern day Baoji). Chen Tai also asked the imperial court of Cao Wei for more reinforcements.

Order of battle

Cao Wei order of battle:
*General Subduing the West (征西将军), Chen Tai
**Acting General Safeguarding the West (代安西将军), Deng Ai
**Inspector of Yong State (雍州刺史), Wang Jing
**General Hu Feng (胡奋)
**General Wang Mi (王秘)Shu Han order of battle:
*General of the Garrison (卫将军), Jiang Wei
**General of Chariots and Cavalry (车骑将军), Xiahou Ba
**Senior General Subduing the West (征西大将军), Zhang Yi

Battle of Gu Pass

Wang Jing, with virtually no military experience, had gravely underestimated the enemy and erroneously believed that the enemy would be tired after the prolonged march, and it would be better not to provide the enemy any chance to rest and regroup, but to defeat them early in a preemptive strike. Wang Jing was confident that he would have a decisive victory because his enjoyed the numerical superiority over the enemy, and unlike his enemy whose supply line was overstretched, his own force on the defensive had no logistic problems. Therefore, Wang Jing ignored Chen Tai’s order of staying in Didao City, and instead led his force ventured out to Gu (故) Pass in the upstream of the Tao River (洮水). Gu Pass was located to the north of modern day Lintao, and it was on the western bank of the Tao River, and this was the place Wang Jing had selected to annihilate the invading enemy who were supposed to be tired and short on supplies, and thus had lower morale. In August, 255, both sides clashed on the western bank of the Tao River (洮水), and Cao Wei suffered a disastrous defeat: the number of soldiers drowned in the Tao River in their attempts to escape alone totalled more than ten thousand, and most of Wang Jing’s troops were lost. Wang Jing was forced to lead his remaining ten thousand soldiers to retreat back to Didao City in the south after crossing the Tao River, and regroup behind the safety of the city wall. The battle on the western bank of Tao River (洮西之战), also known as the Battle of the Gu Pass (故关之战), was the greatest victory Jiang Wei had achieved in his northern expeditions, and it was also his last.

After the initial victory, Zhang Yi accurately realized the supply problems Shu Han faced, and suggested to Jiang Wei to withdraw. Jiang Wei, wanting to ride his initial victory to take the Didao City, angrily turned down the suggestion and besieged Didao City. As the news of Wang Jing going out to engage Jiang Wei reached Chen Tai, he immediately and accurately predicted that Cao Wei would suffer a defeat and thus ordered his cavalry to the rescue, and he would lead the infantry himself to follow. Chen Tai also wrote an urgent message to the imperial court of Cao Wei for additional reinforcements. When the news of disaster reached the imperial capital of Cao Wei, Luoyang, the imperial court was worried that Chen Tai alone would not be able to salvage the situation. Deng Ai, the Changshui (长水) Captain (校尉) of Cao Wei who had just arrived in the capital, was named as the Acting General Safeguarding the West (代安西将军), and was sent on his way to western Gansu to assist Chen Tai. As soon as Deng Ai had left the imperial capital, Sima Zhao also put his uncle Grand Commandant (太尉) Sima Fu in charge of Guanzhong to help coordinate logistics for Cao Wei forces for the war efforts. Sima Zhao would not dare to leave the imperial capital himself as he had just succeeded his elder brother and thus must remain in the capital to consolidate his position.

trategies

When the news of the siege of the Didao City reached Chen Tai initially, he believed that the city would not fall that easily, but the reinforcement he sent was definitely not enough, thus he asked the imperial court of Cao Wei for more. Most imperial subjects in the imperial court of Cao Wei, however, was worried that after the disastrous defeat, Wang Jing would not last until the reinforcement arrived. With the loss the strategically important post, the enemy would have the absolute geographical advantage and the four commandaries in western Gansu would be lost for sure. Therefore, it would be better to take more time to gather a much greater army to fight a long war to regain the control of the region instead of wasting resources on a seemingly impossible task that would be destined to fail. Chen Tai should be called back to prepare the much larger force for the upcoming long term struggle. Sima Zhao brushed such concerns aside, pointing out that if even Zhuge Liang could not achieve the goal of taking four commandaries in western Gansu in his northern expeditions when he was alive, Jiang Wei would be certainly not able to achieve the same. It would not be easy to immediately take Didao City and the invading enemy would soon run out supplies, and thus Chen Tai's request for immediate reinforcements was absolutely correct. As Chen Tai led his force to Shanggui (上邽, modern day Tianshui), other reinforcements included those led by Deng Ai, Hu Fen (胡奋), and Wang Mi (王秘) also arrived. Just like in the imperial court of Cao Wei, the frontline commanders also sharply disagreed initially on their next move. Deng Ai’s opinion was echoed by everyone except Chen Tai, whom Deng Ai attempted to convince by claiming that after the devastating defeat of Wang Jing which caused most of the Cao Wei crack troops of the local region to be annihilated, the morale of the enemy was extremely high and the that of their own troops was low. Cao Wei reinforcement was gathered in haste after the defeat, so it was difficult to achieve victory over the enemy at this time. It would be wise to sacrifice some local interests in order to save the overall interest. Therefore, it might be better to leave Wang Jing and his Didao City to fend for himself, and wait until the enemy became tired and less alert, and then launch a counteroffensive.

Chen Tai opposed Deng Ai’s idea that was agreed by everyone else. Chen Tai reasoned that the Jiang Wei’s advantage was to fight a quick battle because he did not enough supply for a prolonged struggle due to logistic problem. Wang Jing was supposed to avoid readily combating the invading enemy in the first place and wait until the enemy exhausted its supplies, and then counterattack only when he joined forces with the reinforcements. Instead, Wang Jing did exactly what Jiang Wei had hoped and rushed to battle and faced a devastating defeat. Had Jiang Wei rode on his initial victory and continue eastward to take important grain production region of Cao Wei, he would have a chance to disrupt Guanzhong, which was truly the real threat. In fact, Jiang Wei might even had a chance to take both Yong (雍) and Liang (凉) provinces if he had done so and gathered support of minorities in the north and northwest. Instead, Jiang Wei had made a grave military blunder in besieging Didao City, which would risk running out the limited supply he had. Attempting to take the city was the worst choice because it would take time to make the preparation, while at the mean time, the defenders had their backs against the wall and would fight to the death to defend the city. This would provide the excellent opportunity to repel the invading Shu Han army because Cao Wei reinforcement enjoyed the geographical advantage for being stationed in the high grounds in the mountains, while it was difficult for Shu Han forces in the plains at the lower level to attack upward. Finally, Chen Tai reminded his subordinates that the morale of the enemy would not last long once their supply begun to run out, and everyone concurred and nobody objected to Chen Tai’s decision. Chen Tai subsequently divided his force into three fronts and pushed toward western Gansu, bypassing Jiang Wei’s force, and reached the mountains to the southeast of Didao City.

Relief

As the siege of Didao City continued, the supply problem begun to take its toll on the overstretched Shu Han force, and there were more bad news for Jiang Wei. The news of Cao Wei reinforcements arrived from Jincheng commandary (金城郡) of Liang (凉) province in the upstream of Tao River, while at the same time, Chen Tai's reinforcements bypassed the Gaocheng Ridge (高城岭, located to the northwest of modern day Weiyuan 渭源 County of Gansu), and took position in the mountains to the southeast of the besieged Didao City. After several failed attempts of attacking the mountain ridge, it was obvious to Shu Han commanders that their hungry soldiers could not dislodge the Cao Wei reinforcements. The reinforcements in the mountains just outside the city wall established the link with the city by means of smoke and drums, and the defenders’ morale was greatly boosted. Chen Tai was well aware that despite the numerical advantage and newly boosted morale, the Cao Wei force was not in a position to counterattack. Instead, Chen Tai deployed a clever tactic by releasing the news of a planned counteroffensive in which the Cao Wei force would attack the Shu Han force from both sides. With the supplies running out, Jiang Wei was forced to concede defeat by retreating on September 25, 255 to Zhongti (钟堤, located to the south of modern day Lintao) at the downstream of Tao River, to the south of Didao City. The battle therefore was concluded with Cao Wei victory. As Wang Jing opened the city gate to welcome Chen Tai, he cordially thanked the latter, revealing that the food left was not enough to last for ten days, and the city would definitely fall if the reinforcements failed to arrive in time. After re-supplying the city and reorganize the defense, Chen Tai and his force returned to Shanggui (上邽).

Aftermath

Although successfully repelling the invading Shu Han force led by Jiang Wei, Cao Wei had suffered a terrible loss. In October, 255, Cao Mao, the emperor of Cao Wei issued an imperial decree in which he ordered the local civilian officials and military officers to devote their sources fully to the relief effort. The military draft and tax levied on the local populace were waived for a year. Cao Mao soon issued another imperial decree in November, 255 to further boost the morale and the support of the local populace by granting amnesty to the local family members left behind by those defected to Shu Han. Merely half a month after his second imperial decree, Cao Mao issued the third imperial decree in which he ordered Chen Tai and Deng Ai to commit all of their forces to fish out all of the remaining cadavers of Cao Wei soldiers in the Tao River, and bury them with other killed in the battle. It was more than a hundred day after the end of the battle, and the devastation was so great that many of the killed still had not been properly buried.

For his brilliant achievement, Chen Tai was recalled to Luoyang, the capital of Cao Wei to be promoted to Imperial Secretariat (尚书), and the position of General Subduing the West (征西将军) was succeeded by Sima Wang, the elder cousin of Sima Zhao and Sima Fu’s son. Deng Ai was no longer the Acting General Safeguarding the West (代安西将军), but was awarded the true rank of General Safeguarding the West (安西将军), and he was put in charge of both Yong (雍) and Liang (凉) provinces. Wang Jing, who was the cause of the initial Cao Wei defeat and subsequent devastation, was reassigned to another position in the capital and the vacant position of Inspector of Yong (雍州刺史) he left behind was filled by Deng Ai’s subordinate, Zhuge Xu (诸葛绪).

Outcome

Although forced to retreat, this battle was actually one of the greatest success Jiang Wei had achieved in his northern expeditions. Unfortunately, the weak Shu Han could not support the large scale logistic needed to sustain the long term siege and consequently, Jiang Wei was forced to admit defeat by retreating like in previous expeditions. For Cao Wei, despite suffering heavy losses, the enemy was nonetheless beaten back, and it would be a matter of time before Cao Wei could fully recover, albeit it would take longer than usual. The battle clearly revealed the strength of the opposing states and it would be Cao Wei and its successor who would eventually unify China once again.

Reference

*"Selected Examples of Battles in Ancient China" Writing Team, "Selected Examples of Battles in Ancient China", 1st Edition, published by Chinese Publishing House & Distributed by New China Bookstore Publishing House in Beijing, 1981 - 1984.
*Yuan, Tingdong, "War in Ancient China", 1st Edition, published by Sichuan Academy of Social Science Publishing House & Distributed by New China Bookstore in Chengdu, 1988, ISBN 7805240582
*Zhang, Xiaosheng, "General View of War of Ancient China", 1st Edition in Xi'an, published by Long March Publishing House in Beijing & Distributed by New China Bookstore in Beijing, 1988, ISBN 7800150313 (set)