Empty Fort Strategy The Empty Fort Strategy is the 32nd of the Chinese Thirty - Six Stratagems . The strategy involves using reverse psychology ( and luck ) to deceive the enemy into thinking that an empty location is full of traps and ambushes , and therefore induce the enemy to retreat . Some examples are listed in the following sections . Cao Cao . According to Cao Cao ' s biography in the " Sanguozhi " , in 195 , the Empty Fort Strategy was used by Cao Cao against Lü Bu ' s forces in one incident at Chengshi ( 乘氏 ; southwest of present - day Juye County , Shandong ) . In the summer of that year , Lü Bu went to Dongmin ( 東緡 ; northeast of present - day Jinxiang County , Shandong ) and gathered about 10 , 000 troops to attack Cao Cao . At that time , Cao Cao had very few soldiers with him , so he set up an ambush and defeated Lü Bu . The " Wei Shu " ( 魏書 ) gave a more detailed account of the ambush . Cao Cao had sent his troops out to collect grain so he had less than 1 , 000 men with him in his base , which was not well defended . When Lü Bu showed up , Cao Cao sent 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 10 " li " south of Cao Cao ' s base and set up his camp there . The following day , Lü Bu came to attack Cao Cao , and by then , Cao Cao had really set up an ambush near the dyke . Lü Bu ' s forces fell into the ambush and were defeated . The " ambush " mentioned in the " Sanguozhi " refers to the ambush that Lü Bu ' s forces fell into on the second day , as described in the " Wei Shu " . The incident is also mentioned in the " Zizhi Tongjian " , written by Sima Guang in the Song Dynasty . However , the " Zizhi Tongjian " account , which combined the " Sanguozhi " and " Wei Shu " accounts , did not mention the events on the first day ( about Cao Cao sending all his available soldiers to defend the base and ordering women to stand guard on the walls ) . Debate . Yi Zhongtian , a professor from Xiamen University , commented on this incident in his book " Pin San Guo " ( 品三国 ) in response to criticism from Fudan University history professor Zhou Zhenhe ( 周振鹤 ) and a web user called " Hongchayangweili " ( 红茶杨威利 ) , after he said in a lecture on the television programme " Lecture Room " that " Cao Cao ' s rights to the invention of the Empty Fort Strategy had been stolen from him " ( referring to this incident in 195 ) . Zhou claimed that the Empty Fort Strategy had never been used in history , so there were no " rights " to its invention ; the web user argued that the incident in 195 does not count as a use of the Empty Fort Strategy . Yi defended his claim , saying that the incident in 195 is valid , because of the circumstances under which it was used , which were very similar to the incidents involving Zhao Yun and Wen 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 the latter came to attack again on the following day . Zhao Yun . The " Yun Biezhuan " ( 雲別傳 ; " Unofficial Biography of ( Zhao ) Yun " ) mentioned an incident about Zhao Yun ( a general under the warlord Liu Bei ) using the Empty Fort Strategy during the Battle of Han River in 219 , fought between Liu Bei and his rival Cao Cao as part of the Hanzhong Campaign . This incident took place after Cao Cao ' s general Xiahou Yuan was defeated and killed in action at the earlier Battle of Mount Dingjun . Cao Cao ' s forces were transporting food supplies to Beishan ( 北山 ) when Liu Bei ' s general Huang Zhong heard about it and led a group of soldiers ( including some of Zhao Yun ' s men ) to seize the supplies . Huang Zhong did not return after a long time so Zhao Yun led tens of horsemen in search of Huang . Zhao Yun encountered Cao Cao ' s forces and engaged them in battle but was outnumbered and was forced to retreat back to his camp , with Cao Cao ' s men in pursuit . Zhang Yi was in Zhao Yun ' s camp and he wanted to close the gates 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 the Han River and drowned . When Liu Bei came to inspect Zhao Yun ' s camp later , he praised Zhao and threw a banquet to celebrate Zhao ' s victory . Wen Ping . The " Weilue " mentioned an incident about the Empty Fort Strategy being used by a general Wen Ping around the time of the Battle of Jiangling in 223 , fought between the forces of the states of Cao Wei and Eastern Wu in the Three Kingdoms period . The Wu emperor Sun Quan led thousands of troops to attack a fortress defended by the Wei general Wen Ping . At that time , there were heavy rains and much of the fortifications were damaged . The civilians in the fortress had retreated to the fields so they could not help the defenders repair the fortifications in time . When Wen Ping heard that Sun Quan had arrived , he was unsure of what to do , but eventually he thought of using deception . 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 . The historian Pei Songzhi commented that the " Weilue " account did not match the original account in Wen Ping ' s biography in the " Sanguozhi " , written by Chen Shou . Chen Shou wrote : " 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 . " Zhuge Liang . One of the best known examples of the use of the Empty Fort Strategy is a fictional episode in the historical novel " Romance of the Three Kingdoms " by Luo Guanzhong , which romanticises the history of the late Han Dynasty and the Three Kingdoms period . This event took place during the first of a series of campaigns ( known as Zhuge Liang ' s Northern Expeditions ) led by Shu Han ' s Zhuge Liang to attack Shu ' s rival state Cao Wei . In the first Northern Expedition , Zhuge Liang ' s efforts to conquer Chang ' an , a strategic city in Wei , were undermined by the Shu defeat at the Battle of Jieting . With the loss of Jieting ( present - day Qin ' an County , Gansu ) , Zhuge Liang ' s current location , Xicheng ( 西城 ; believed to be located 120 " li " southwest of present - day Tianshui , Gansu ) , became exposed and was in peril 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 , 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 boys flanking him . He put on a calm and composed image by playing his guqin . When the Wei army led by Sima Yi arrived , Sima was surprised by the scene 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 an ambush upon seeing Zhuge ' s relaxed composure . As a topic of academic study . Christopher Cotton , an economist from the University of Miami , and Chang Liu , a PhD Student in the Department of Finance at the Georgia Institute of Technology , used game theory to assess the Chinese military legends of Li Guang and his 100 horsemen ( 144 BC ) , and Zhuge Liang and the Empty City ( 228 AD ) . In the case of the military legends , the researchers found that bluffing arose naturally as the optimal strategy in each situation . The findings were published under the title " 100 Horsemen and the empty city : A game theoretic examination of deception in Chinese military legend " in the " Journal of Peace Research " in 2011 . Historicity . The basis for this story in " Romance of the Three Kingdoms " came from annotations to Zhuge Liang ' s biography in the historical text " Sanguozhi " , written by Chen Shou . The annotations came from " San Shi " ( 三事 ) written by Guo Chong ( 郭沖 ) , and were added by Pei Songzhi to Zhuge Liang ' s biography . Guo Chong ' s account of the incident is as follows : After adding Guo Chong ' s account to Zhuge Liang ' s biography , Pei Songzhi made some personal comments about the account . He pointed out some fallacies in the account and dismissed it as fiction . He wrote : Evidence from historical sources indicate that Sima Yi was indeed not present around the Jieting area ( in present - day Gansu ) at that time . The Battle of Jieting took place in 228 but Sima Yi ' s biography in the " Book of Jin " claimed that in 227 , Sima Yi was stationed at Wancheng in the north of Jing Province . He led an army to suppress a rebellion by Meng Da at Xincheng ( 新城 ) in northwestern Jing Province , and returned to Wancheng after his victory . Later , he was summoned to the capital Luoyang to meet the Wei emperor Cao Rui , who consulted him on some affairs before ordering him to return to the garrison at Wancheng . Sima Yi only came into direct confrontation with Zhuge Liang after 230 . Yi Zhongtian , a professor from Xiamen University , commented on this incident in his book " Pin San Guo " ( 品三国 ) . He pointed three fallacies in the story : Battle of Mikatagahara . In 1572 , during the Sengoku Period in Japan , Tokugawa Ieyasu used the tactic during his retreat in the Battle 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 the enemy forces , led by Baba Nobuharu and Yamagata 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 .