兵贵神速 — “In military operations, swiftness is of paramount importance”

The idiom "Bing Gui Shen Su" (兵贵神速), meaning "speed is precious in war," originates from a historical account involving the strategist Guo Jia and the warlord Cao Cao during the Three Kingdoms period. After Cao Cao defeated Yuan Shao and killed Yuan Shao's eldest son Yuan Tan, Yuan Shao's other two sons, Yuan Shang and Yuan Xi, fled to the Wuhuan chieftain Tādùn in the Liao River basin. Tādùn then began to harass the Han border.

Cao Cao intended to conquer Yuan Shang and Tādùn, but some officials worried that Liu Biao, who had Liu Bei under his command in Jingzhou, might seize the opportunity to attack Cao Cao's rear. Guo Jia, known for his wisdom, analyzed the situation. He advised Cao Cao, saying, "You now command great prestige, but the Wuhuan, being in a remote region, will not be prepared for an attack. A swift surprise assault will surely eliminate them. If we delay, Yuan Shang and Yuan Xi might recover their strength, unite with the Wuhuan, and Tādùn could grow ambitious, potentially causing us to lose control of Jizhou and Qingzhou. As for Liu Biao, he is merely a talker who knows his abilities are inferior to Liu Bei's and will not fully trust or utilize Liu Bei. Liu Bei, feeling underutilized, will not exert himself much for Liu Biao. Therefore, you can embark on this distant expedition against the Wuhuan without worries about your rear."

Convinced by Guo Jia, Cao Cao led his army. Upon reaching Yixian, Guo Jia offered further counsel: "Speed is paramount in warfare. As we are now embarking on a campaign thousands of li away, with many supplies, our advance will be slow. If the Wuhuan learn of our approach, they will prepare. It would be better to leave our heavy equipment behind, march with light forces, and advance at double speed to launch a surprise attack when the enemy is unprepared. This will guarantee a decisive victory."

Cao Cao followed Guo Jia's brilliant strategy. His troops marched rapidly, reaching Tādùn's stronghold unexpectedly. The Wuhuan people were caught completely off guard and utterly defeated. Tādùn was killed, and Yuan Shang and Yuan Xi fled to Liaodong, where they were eventually killed by the prefect Sun Kang. This decisive victory, achieved through unexpected speed and surprise, perfectly illustrates the principle that "speed is precious in war."