| Empty Fort Strategy | |||||||
|---|---|---|---|---|---|---|---|
 Zhuge Liang againstSima Yi with his sonsSima Zhao andSima Shi, as depicted in the artworkRuse with an Empty City | |||||||
| Traditional Chinese | 空城計 | ||||||
| Simplified Chinese | 空城计 | ||||||
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TheEmpty Fort Strategy involves usingreverse psychology to deceive the enemy into thinking that an empty location is full of traps and ambushes, and therefore induce the enemy to retreat. It is listed as the 32nd of theThirty-Six Stratagems. Some examples are listed in the following sections.
According to theSanguozhi, in 195, the Empty Fort Strategy was used by the warlordCao Cao against his rivalLü Bu in one incident at Chengshi County (乘氏縣; southwest of present-dayJuye County,Shandong). In the summer of that year, Lü Bu went to Dongmin County (東緡縣; northeast of present-dayJinxiang County, Shandong) and gathered about 10,000 troops to attack Cao Cao. At the time, Cao Cao had very few soldiers with him, but he set up an ambush and managed to defeat Lü Bu.[1]
TheWei Shu (魏書) gave a more detailed account of the ambush. Cao Cao had sent most of his troops out to collect grain so he had less than 1,000 men available in his base, which could not be well defended with so few men. When Lü Bu showed up, Cao Cao ordered all his available soldiers to defend the base and even ordered women to stand guard on the walls. To the west of Cao Cao's base was a dyke, and to its south was a deep forest. Lü Bu suspected that there was an ambush, so he told his men, "Cao Cao is very cunning. We must not fall into his ambush." He then led his troops to 10li (Chinese miles) south of Cao Cao's base and set up his camp there. The next day, Lü Bu came to attack Cao Cao, and by then, Cao Cao had really set up an ambush near the dyke with the soldiers that had returned from gathering the grain. Lü Bu's forces fell into the ambush and were defeated.[2]
The "ambush" mentioned in theSanguozhi refers to the ambush that Lü Bu's forces fell into a trap on the second day, as described in theWei Shu. The incident is also mentioned inSima Guang'sZizhi Tongjian. However, theZizhi Tongjian account, which combined theSanguozhi andWei Shu accounts, did not mention the events on the first day – which were about Cao Cao sending all his available soldiers to defend the base and ordering women to stand guard on the walls.[3]
Yi Zhongtian, a history professor fromXiamen University, commented on this incident in his bookPin San Guo (品三国) in response to criticism fromFudan University historianZhou Zhenhe and an online commentator known as "Hongchayangweili" (红茶杨威利). Earlier on, Yi referred to this incident when he said in a lecture on the television programmeLecture Room that "Cao Cao's rights to the invention of the Empty Fort Strategy had been stolen from him". Zhou claimed that the Empty Fort Strategy had never been used in history before so there were no "rights" to its invention; the online commentator argued that the incident does not count as a use of the Empty Fort Strategy.
Yi defended his claim and said that the incident in 195 is valid because of the circumstances under which it was used, which were very similar to the incidents involvingZhao Yun andWen Ping (see the sections below). Cao Cao was trying to confuse Lü Bu by making use of the geographical features (the "deep forest") and by ordering women to stand guard on the walls, so as to make Lü Bu suspect that he had set up an ambush in the "deep forest" and lure Lü Bu to attack his "weakly defended" base by deploying women as soldiers to show how "desperate" he was to set up a defence. The ploy worked because it made Lü Bu hesitate when he wanted to attack. Cao Cao had bought sufficient time to set up a real ambush, and he defeated Lü Bu when he came to attack again on the following day.[4]
TheZhao Yun Biezhuan (趙雲別傳;Unofficial Biography of Zhao Yun) mentioned an incident aboutZhao Yun, a general under the warlordLiu Bei, using the Empty Fort Strategy during theBattle of Han River in 219, fought between Liu Bei and his rivalCao Cao as part of theHanzhong Campaign.
This incident took place after Cao Cao's generalXiahou Yuan was defeated and killed in action at the earlierBattle of Mount Dingjun. Cao Cao's forces were transporting food supplies to the north hill when Liu Bei's generalHuang Zhong, heard about it and led a group of soldiers, including some of Zhao Yun's men, to seize the supplies. When Huang Zhong did not return after a long time, Zhao Yun led tens of horsemen in search of Huang. Zhao Yun's search party encountered Cao Cao's forces and engaged them in battle but were outnumbered and was forced to retreat back to camp with Cao Cao's men in pursuit. Zhao Yun's subordinateZhang Yi wanted to close the gates of the camp to prevent the enemy from entering. However, Zhao Yun gave orders for the gates to be opened, all flags and banners to be hidden, and the war drums silenced. Cao Cao's forces thought that there was an ambush inside Zhao Yun's camp so they withdrew. Just then, Zhao Yun launched a counterattack and his men beat the war drums loudly and fired arrows at the enemy. Cao Cao's soldiers were shocked and thrown into disarray. Some of them trampled on each other while fleeing in panic, and many of them fell into theHan River in their haste to get away and drowned. When Liu Bei came to inspect the camp later, he praised Zhao Yun and held a banquet to celebrate his victory.[5]
TheWeilüe mentioned an incident about the Empty Fort Strategy being used by a generalWen Ping during a battle between the forces of the states ofCao Wei andEastern Wu in theThree Kingdoms period. It is not clear which battle this was, but it could have been theBattle of Jiangling of 223.
The Wu leaderSun Quan led thousands of troops to attack a fortress defended by the Wei general Wen Ping. At the time, there were heavy rains and many fortifications were damaged. The civilians in the fortress had retreated to the fields further back so they could not help with repairs to the fortifications, and some repairs were still uncompleted when Sun Quan arrived with his men. When Wen Ping heard that Sun Quan had arrived, he was unsure of what to do, but eventually formulated a plan to deceive him. He ordered everyone in the fortress to stay under cover while he hid behind the walls, creating an illusion of an empty fortress. As Wen Ping expected, Sun Quan became suspicious and he said to his subordinates, "The northerners regard this man (Wen Ping) as a loyal subject, which is why they entrusted him with defending this commandery. Now, as I approach, he does not make any move. It must be either that he has something up his sleeve or that his reinforcements have arrived." Sun Quan then withdrew his forces.[6]
The historianPei Songzhi commented that theWeilüe account did not match the original account in theSanguozhi. TheSanguozhi mentioned: "Sun Quan led 50,000 troops to besiege Wen Ping at Shiyang (石陽). The situation was very critical but Wen Ping put up a firm defence. Sun Quan withdrew his forces after more than 20 days, and Wen Ping led his men to attack them as they were retreating and defeated them."[7]
One of the best known examples of the use of the Empty Fort Strategy is a fictional incident in the novelRomance of the Three Kingdoms, which romanticises historical events in the lateHan dynasty and theThree Kingdoms period. This event took place during the first of a series of campaigns – known asZhuge Liang's Northern Expeditions – led byShu Han'schancellorZhuge Liang to attack Shu's rival state,Cao Wei.
In the first Northern Expedition, Zhuge Liang's efforts to conquer the Wei cityChang'an were undermined by the Shu defeat at theBattle of Jieting. With the loss of Jieting (present-dayQin'an County,Gansu), Zhuge Liang's current location, Xicheng (西城; believed to be located 120li southwest of present-dayTianshui, Gansu), became exposed and was in danger of being attacked by the Wei army. In the face of imminent danger, with the main Shu army deployed elsewhere and only a small group of soldiers in Xicheng with him, Zhuge Liang came up with a ploy to hold off the approaching enemy.
Zhuge Liang ordered all the gates to be opened and instructed soldiers disguised as civilians to sweep the roads while he sat on the viewing platform above the gates with two page boys by his side. He put on a calm and composed image by playing hisguqin. When the Wei army led bySima Yi arrived, Sima was surprised by the sight before him and he ordered a retreat after suspecting that there was an ambush inside the city. Zhuge Liang later explained that his strategy was a risky one. It worked because Zhuge Liang had a reputation for being a careful military tactician who hardly took risks, so Sima Yi came to the conclusion that there was certainly an ambush upon seeing Zhuge's relaxed composure.[8]
Christopher Cotton, an economist from theQueen's University, and Chang Liu, a graduate student, usedgame theory to model the bluffing strategies used in the Chinese military legends ofLi Guang and his 100 horsemen (144 BC), and Zhuge Liang and the Empty City (228 AD). In the case of these military legends, the researchers found that bluffing arose naturally as the optimal strategy in each situation. The findings were published under the title100 Horsemen and the empty city: A game theoretic examination of deception in Chinese military legend in theJournal of Peace Research in 2011.[9][10]
The basis for this story inRomance of the Three Kingdoms is an anecdote shared by one Guo Chong (郭沖) in the earlyJin dynasty (266–420).[11] In the fifth century,Pei Songzhi added the anecdote as an annotation to Zhuge Liang's biography in the third-century historical textSanguozhi. The anecdote is as follows:
Zhuge Liang garrisoned at Yangping (陽平; around present-dayHanzhong,Shaanxi) and orderedWei Yan to lead the troops east. He left behind only 10,000 men to defend Yangping. Sima Yi led 200,000 troops to attack Zhuge Liang and he took a shortcut, bypassing Wei Yan's army and arriving at a place 60li away from Zhuge Liang's location. Upon inspection, Sima Yi realised that Zhuge Liang's city was weakly defended. Zhuge Liang knew that Sima Yi was near, so he thought of recalling Wei Yan's army back to counter Sima Yi, but it was too late already and his men were worried and terrified. Zhuge Liang remained calm and instructed his men to hide all flags and banners and silence the war drums. He then ordered all the gates to be opened and told his men to sweep and dust the ground. Sima Yi knew that impression that Zhuge Liang was a cautious and prudent man, and he was baffled by the sight before him and suspected that there was an ambush. He then withdrew his troops. The following day, Zhuge Liang clapped his hands, laughed, and told an aide that Sima Yi thought that there was an ambush and had withdrawn. Later, his scouts returned and reported that Sima Yi had indeed retreated. Sima Yi was very upset when he later found out about the ruse.[12]
After adding the anecdote to Zhuge Liang's biography, Pei Songzhi wrote a short commentary as follows:
When Zhuge Liang garrisoned at Yangping, Sima Yi was serving as the Area Commander ofJing Province and he was stationed at Wancheng (宛城; present-dayWancheng District,Nanyang,Henan). He only came into confrontation with Zhuge Liang inGuanzhong afterCao Zhen's death (in 231). It was unlikely that the Wei government ordered Sima Yi to lead an army from Wancheng to attack Shu via Xicheng (西城; present-dayAnkang, Shaanxi) because there were heavy rains at the time (which obstructed passage). There were no battles fought at Yangping before and after that period of time. Going by Guo Chong's anecdote, if Sima Yi did lead 200,000 troops to attack Zhuge Liang, knew that Zhuge Liang's position was weakly defended, and suspected that there was an ambush, he could have ordered his troops to surround Zhuge Liang's position instead of retreating. Wei Yan's biography mentioned: "Each time Wei Yan followed Zhuge Liang to battle, he would request to command a separate detachment of about 10,000 men and take a different route and rendezvous with Zhuge Liang's main force atTong Pass. Zhuge Liang rejected the plan, and Wei Yan felt that Zhuge Liang was a coward and complained that his talent was not put to good use." As mentioned in Wei Yan's biography, Zhuge Liang never agreed to allow Wei Yan to command a separate detachment of thousands of troops. If Guo Chong's anecdote was true, how was it possible that Zhuge Liang would allow Wei Yan to lead a larger army ahead while he followed behind with a smaller army? Guo Chong's anecdote was endorsed by the Prince of Fufeng (Sima Jun, a son of Sima Yi). However, the story puts Sima Yi in a negative light, and it does not make sense for a son to approve a story which demeans his father. We can tell that this anecdote is fake after reading the sentence "the Prince of Fufeng endorsed Guo Chong's anecdote".[13]
Evidence from historical sources indicate that Sima Yi was indeed not in Jieting at the time. The Battle of Jieting took place in 228 but Sima Yi's biography in theBook of Jin claimed that in 227, Sima Yi was stationed at Wancheng in the north ofJing Province. He led an army to suppress arebellion byMeng Da at Xincheng (新城; in present-day northwesternHubei), and returned to Wancheng after his victory. Later, he went to the imperial capitalLuoyang to meet the Wei emperorCao Rui, who consulted him on some affairs before ordering him to return to Wancheng.[14] Sima Yi only engaged Zhuge Liang in battle after 230.[15]
Yi Zhongtian, a professor fromXiamen University, commented on this incident in his bookPin San Guo (品三国). He pointed out three problems in the story:[4]
According to historical sources such as theOld Book of Tang,New Book of Tang andZizhi Tongjian,Li Yuan, the founding emperor of theTang dynasty, used a similar strategy in 618 CE in a battle against theGöktürks before he started his rebellion against theSui dynasty. In early 618, Li Yuan was still a general in the Sui army and was based in Jinyang (晉陽; present-dayTaiyuan,Shanxi). When he heard rumours thatEmperor Yang of Sui wanted to execute him, he started making preparations for a rebellion against the Sui dynasty to save himself. In May 618, the Göktürks allied with the warlordLiu Wuzhuo to attack the Sui dynasty in order to gain territory. Jinyang became one of their targets.
Around the time, Li Yuan had just arrested Wang Wei (王威) and Gao Junya (高君雅), two officials sent by Emperor Yang to spy on him. He was also still busy plotting his rebellion.[18] Moreover, he was also not prepared for a battle against the Göktürks because of two reasons. Firstly, Göktürk cavalrymen were so powerful that Li Yuan was not confident that his troops could defeat them. Secondly, even if Li Yuan defeated them in battle, he would nonetheless suffer significant losses that would undermine his rebellion against the Sui dynasty.
Li Yuan thus ordered his soldiers to hide in Jinyang and leave the city gates wide open.Shibi Khan, leading a force of Göktürk cavalrymen, saw that the city appeared to be deserted and feared that there might be an ambush, so he did not enter. Li Yuan then ordered his sonLi Shimin and subordinatePei Ji to make their troops beat war drums loudly in the empty camps they had set up earlier, so as to create an illusion that reinforcements had arrived in Jinyang. Shibi Khan was so frightened that he retreated after two days.[19]
Many traditions say that in 1572, during theSengoku Period in Japan,Tokugawa Ieyasu used the tactic during his retreat in theBattle of Mikatagahara. He commanded that the fortress gates remain open, and that braziers be lit to guide his retreating army back to safety. One officer beat a large war drum, seeking to add encouragement to the returning men of a noble, courageous retreat. When Takeda forces led byBaba Nobuharu andYamagata Masakage heard the drums, and saw the braziers and open gates, they assumed that Tokugawa was planning a trap, and so they stopped and made camp for the night. The authenticity of this story has been disputed by some, however, as it appears to be copied straight from Zhuge Liang's story, perhaps in an attempt to embellish Tokugawa's career.[20]
reprinted from materials provided by University of Miami
