Empty Fort Strategy

The Empty Fort Strategy (zh-tsp|t=空城計|s=空城计|p=Kōngchéng jì) is the 32nd strategy from the Chinese Thirty-Six Strategies. The strategy involves using reverse psychology (and luck) to deceive the enemy into thinking that an empty fort is full of traps and ambushes, and therefore retreat. This tactic is made famous by Zhuge Liang's use in a fictitious encounter between the Kingdom of Shu and the Kingdom of Wei in the "The Romance of the Three Kingdoms" novel by Luo Guanzhong.

Examples

Fictional account in the Romance of the Three Kingdoms

In the legend from "The Romance of the Three Kingdoms", Zhuge Liang led six expeditions to the north from Hanzhong through Qishan in hopes of capturing Chang'an. In the 1st expedition, his efforts were undermined by the loss of Jieting, a passageway into Hanzhong. This was due to the defiance of Ma Su, who refused to listen to the Prime Minister's orders to barricade the pathway. With the loss of Jieting, Zhuge Liang's current location, Xicheng (西城), is in great danger. Having sent out all the troops and left with a handful of civil officials, Zhuge Liang decides to use a ploy to ward off the advancing Wei army.

Zhuge Liang ordered all the gates to be opened and had civilians sweeping the roads while he sat high up on the gates calmly playing his zither with two children beside him. When the Wei commander and strategist Sima Yi approached the fort with the Wei army, he was puzzled by the scenery and ordered his troops to retreat.

Zhuge Liang later told the bewildered civil officials that the strategy only worked because Sima Yi is a man of suspicion, the latter having personally witnessed the success of Zhuge Liang's highly effective ambushing and misdirection tactics many times before. Furthermore, Zhuge Liang had a reputation as a keen but extremely careful military tactician who rarely took risks. Zhuge's well-known caution coupled with Sima Yi's own suspicious nature led Sima Yi to the conclusion that entry into the apparently empty city would have drawn his troops into an ambush. It is unlikely the same strategy would have worked on someone else, and indeed Sima Yi's son Sima Zhao saw through the ruse immediately and counselled his father against retreat.

Because of the lack of historical evidence and lack of logic, historians generally consider this encounter a creation of Luo Guanzhong and common folklore.

Battle of Hanzhong

While Zhuge Liang's use was fictional, contemporary Shu officer Zhao Yun had used the same strategy earlier in history.

In AD 219, Liu Bei and Cao Cao were battling over the control of Hanzhong. Cao Cao had huge supplies of rice stocked up near the North Mountain. Zhao Yun sent his soldiers with Huang Zhong to attack Cao Cao’s army and to capture the provisions. Huang Zhong did not return on time. Along with dozens of men, Zhao Yun went out of his camp to look for Huang. Cao Cao’s main force was marching at that time, so Zhao Yun ran into Cao’s vanguards. Not soon after the two sides commenced to engage in battle, Cao Cao’s main force arrived. Zhao Yun fought his way out toward his own camp. When he found out his lieutenant general Zhang Zhu (張著) was wounded and fell behind, he went back to rescue him.

Cao's army pursued Zhao Yun to his camp. At that time, the Administrator of Mianyang (沔陽), Zhang Yi, was at Zhao Yun’s camp. Zhang thought it best to have all the gates closed in order to defend the camp. However, upon entering the camp, Zhao Yun ordered all banners to be dropped and hidden, all drums to be silenced, and the gates to be left completely open. Suspicious of an ambush, Cao Cao and his army hastily retreated. Then Zhao Yun ordered his drummers to beat drums as loudly as they could, while his archers rain arrows down on Cao’s men. The stunned Cao army was completely routed. Attempting to escape, Cao soldiers rushed toward the Han River, and in confusion and panic many were pushed into the river, and drowned.

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.

Cultural references

*In Chinese, the act of leaving the house door unlocked is sometimes called "setting up an empty fort strategy". (擺空城計)
*The Portal Three Kingdoms expansion of the card games include a card named "Empty City Ruse", referring to Zhuge Liang's use of this strategy.