<P> 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 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 . </P> <P> Christopher Cotton, an economist from the Queen's University, and Chang Liu, a graduate student, used game theory to model the bluffing strategies used in 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 these 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 . </P> <P> The basis for this story in Romance of the Three Kingdoms is an anecdote shared by one Guo Chong (郭 沖) in the early Jin dynasty (265--420). In the fifth century, Pei Songzhi added the anecdote as an annotation to Zhuge Liang's biography in the third - century historical text Sanguozhi . The anecdote is as follows: </P> <P> Zhuge Liang garrisoned at Yangping (陽平; around present - day Hanzhong, Shaanxi) and ordered Wei 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 60 li 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 was under the impression that Zhuge Liang was cautious and prudent, 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 retreated . Later, his scouts returned and reported that Sima Yi had indeed retreated . Sima Yi was very upset when he found out later . </P>

Chinese general who won the siege by making tea