偃旗息鼓 — “To lower banners and silence drums”

It is recorded in "Records of the Three Kingdoms: Biography of Zhao Yun in Shu" that in one battle, Shu general Huang Zhong killed Cao general Xiahou Yuan and seized a strategic location. Cao Cao was furious, moved his grain depot to the foot of Beishan by the Han River, and personally led an army of 200,000 to launch a major attack on Yangping Pass.

Huang Zhong and Zhang Zhu conspired to burn and plunder Wei's military provisions at night. Before leaving, Zhao Yun agreed on a return time with them, promising to lead troops out to reinforce them if they didn't return by the deadline. They encountered Cao Cao's personal command. Zhao Yun fought fiercely with Cao's army, routing them completely, and rescued Huang Zhong and Zhang Zhu.

Cao Cao did not give up easily; he commanded a large force to pursue Zhao Yun, heading straight for the Shu camp. Zhao Yun's deputy, Zhang Yi, seeing Zhao Yun had retreated to his camp and the pursuing enemy was fierce, intended to close the camp gate to defend.

Zhao Yun ordered the camp gates to be opened wide, banners lowered and drums silenced, preparing to let Cao's army in; at the same time, he ordered archers and crossbowmen to ambush inside and outside the camp, then stood alone at the gate, waiting for the enemy. The naturally suspicious Cao Cao pursued to the camp gate, thinking, "With the gates wide open, there must be an ambush," and hastily ordered a retreat.

Just as Cao Cao turned to retreat, the Shu camp erupted with gongs and drums, shouts of battle echoing through the sky, and arrows flew like rain towards Cao's army. Cao's army panicked, scrambling to escape, trampling over each other. Zhao Yun seized the opportunity to capture Cao's provisions, killed a large number of Cao's soldiers, and returned triumphantly to camp.