一鼓作气 — “To accomplish something in one sustained, vigorous effort”

During the Spring and Autumn period, the powerful State of Qi launched an attack on the State of Lu (both in present-day Shandong Province). Lu was much weaker than Qi, but surprisingly, Lu emerged victorious. According to "Zuo Zhuan" (Commentary of Zuo), this victory was largely due to the shrewd planning of Cao Gui.

Cao Gui was not a military general or a civil official, but he deeply understood military strategy. When he learned of Qi's invasion and Duke Zhuang of Lu's preparations for resistance, he proactively sought an audience with the Duke. His relatives and neighbors advised him, "State affairs are managed by high officials who eat meat every day; why bother yourself?" Cao Gui responded, "Those officials are short-sighted and lack foresight."

Upon meeting Duke Zhuang, Cao Gui first emphasized that gaining the people's trust was crucial political preparation before battle and a guarantee of victory. He also requested permission to join the battle. Thus, Duke Zhuang allowed him to share his chariot.

At Changshao, the Qi and Lu armies met. Both sides formed their battle arrays, and the fight was about to begin. The Qi army began beating their war drums vigorously, preparing to advance. Duke Zhuang was also ready to order his drums beaten in response, but Cao Gui stopped him, saying, "Wait a moment." Seeing no reaction from the Lu army, the Qi army beat their drums again. This happened three times; the Qi army beat their drums three times, but the Lu army remained still. Only after Qi's third drum beat did Cao Gui say, "Now we can advance!" The Lu army's war drums then sounded, and an order to charge was given. The soldiers let out a roar, rushing into the enemy formation with irresistible force. The Qi army suffered a crushing defeat and fled in disarray.

Just as Duke Zhuang was about to order a pursuit, Cao Gui again restrained him. He dismounted, carefully examined the wheel tracks of the retreating Qi chariots, and then climbed onto the front crossbar of the chariot to observe the enemy's retreat. He then declared, "Now we can pursue them!" Duke Zhuang immediately ordered the pursuit. The Lu army, capitalizing on their victory, chased the Qi forces entirely out of their territory.

Duke Zhuang, however, did not understand Cao Gui's commands. Cao Gui explained, "War depends on courage. With the first drum beat, morale is highest; with the second, it wanes; with the third, it's exhausted. When their morale is exhausted and ours is high, we conquer them."

Cao Gui further added, "We couldn't underestimate the Qi army; they might have set an ambush, feigning defeat to lure us in. I saw their wheel tracks were chaotic and their flags drooping, which reassured me that they were genuinely fleeing in panic, and then I gave the order to pursue." ("Chaotic tracks" and "drooping flags" indicated a desperate and disorderly retreat).

The idiom "一鼓作气" (yī gǔ zuò qì - make a sustained effort), along with "再衰三竭" (zài shuāi sān jié - morale wanes and is exhausted) and "辙乱旗靡" (zhé luàn qí mí - chaotic tracks and drooping flags), all originate from this "Cao Gui's Battle Strategy" story recorded in "Zuo Zhuan - Duke Zhuang's Tenth Year." "一鼓作气" means to exert all one's effort while enthusiasm and vigor are high at the outset of any undertaking.