Empty Fort Strategy
In May 618, the Göktürks allied with the warlord Liu 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. 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 son Li Shimin and subordinate Pei 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.

Battle of Mikatagahara: Many traditions say that 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 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. 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.

References: 
Chen, Shou. Records of the Three Kingdoms (Sanguozhi).
Fang, Xuanling. Book of Jin (Jin Shu).
Liu, Xu. Old Book of Tang (Jiu Tang Shu).
Luo, Guanzhong. Romance of the Three Kingdoms (Sanguo Yanyi).
Ouyang, Xiu and Song Qi. New Book of Tang (Xin Tang Shu).
Pei, Songzhi. Annotations to Records of the Three Kingdoms (Sanguozhi zhu).
Sima, Guang. Zizhi Tongjian.