Zhao Yun's subordinate Zhang 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.

Just then, Zhao Yun launched a counterattack and his men beat the war drums loudly and fired arrows at the enemy.

[5] The Weilüe mentioned an incident about the Empty Fort Strategy being used by a general Wen Ping during a battle between the forces of the states of Cao Wei and Eastern Wu in the Three Kingdoms period.

The Wu leader Sun Quan led thousands of troops to attack a fortress defended by the Wei general Wen Ping.

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.

In the first Northern Expedition, Zhuge Liang's efforts to conquer the Wei city Chang'an were undermined by the Shu defeat at the Battle of Jieting.

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.

[8] 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).

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.

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 (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 text Sanguozhi.

The anecdote is as follows: Zhuge Liang garrisoned at Yangping (陽平; around present-day Hanzhong, Shaanxi) and ordered Wei Yan to lead the troops east.

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.

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day, Zhuge Liang clapped his hands, laughed, and told an aide that Sima Yi thought that there was an ambush and had withdrawn.

[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 of Jing Province and he was stationed at Wancheng (宛城; present-day Wancheng District, Nanyang, Henan).

It was unlikely that the Wei government ordered Sima Yi to lead an army from Wancheng to attack Shu via Xicheng (西城; present-day Ankang, Shaanxi) because there were heavy rains at the time (which obstructed passage).

He led an army to suppress a rebellion by Meng Da at Xincheng (新城; in present-day northwestern Hubei), and returned to Wancheng after his victory.

Later, he went to the imperial capital Luoyang to meet the Wei emperor Cao Rui, who consulted him on some affairs before ordering him to return to Wancheng.

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.

Secondly, even if Li Yuan defeated them in battle, he would nonetheless suffer significant losses that would undermine his rebellion against the Sui dynasty.

One officer beat a large war drum, seeking to add encouragement to the returning men of a noble, courageous retreat.

When Takeda 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.