Duke Zhuang asked, "How can we defeat Qi?" Cao Gui said: "War should be adapted to the ever-changing battlefield, and we must never decide what fixed tactics to take out of thin air in advance. I am willing to go out with your majesty and count according to the actual situation. " Knowing that he was right, Zhuang took it to meet the enemy. Qi and Lu armies occupied positions in Changshou (now northeast of Laiwu, Shandong) (see the battle of Changshou). Because the general Bao of the State of Qi marched smoothly and had the heart of underestimating the enemy, he ordered the drums to advance first. The Qi army let out a cry and rushed to the Lujun position. When Zhuang Gong saw this, he also wanted to beat the drums. Cao Gui quickly stopped it, and told Zhuang Gong to order the whole army to keep their positions strictly, and not to make any disturbance or noise. Whoever fights without authorization will be beheaded. LuJun didn't move, but Qi Jun couldn't break the front and had to retreat. Bao Shu Ya ordered the second drumming, and the Qi army rallied and rushed to Lujun's position again. Lu array did not move, and the Qi army retreated again. Bao saw that Lu Jun couldn't get out twice, thinking it was stage fright, and ordered the third drumming. At this time, Cao Gui decisively called Zhuanggong to drum and charge. With the drums, ShaSheng suddenly broke out in the Lu array, and the soldiers rushed over like tigers, as fast as lightning. Qi army was killed to pieces, stripped of armor, and fled in a mess. Son Yong was also shot to death by Duke Zhuang of Lu. Seeing that the Qi army was defeated, Zhuang Gong wanted to order an immediate pursuit. Cao Gui quickly said, "Don't worry." He carefully examined the rut of the Qi army's escape, looked at the crossbar in the direction of the Qi army's escape for a while before boarding the chariot, and asked Zhuang Gong to order full pursuit. Lu Jun pursued for more than 30 miles, captured many Qi troops and countless trench, and returned home in triumph.

After the war, Duke Zhuang asked Cao Gui why he ordered the attack when the Qi army played drums for the third time. Cao Gui said; "Fighting mainly depends on morale, and playing drums is to boost morale. The first drum attack, high morale; The second drum attack, morale has declined; By the time the drum was played for the third time, the morale was gone. However, our army has high morale and naturally defeated the other side. " Zhuang Gong asked again, "Why did the Qi army run away? Why not let them catch up right away? " Cao Gui said: "The confrontation between great powers is false and true. Although the Qi army is retreating, it is especially necessary to guard against fraud. I looked at it and hit it. " Zhuanggong was deeply impressed and said, "You are really a strategist!" Immediately worshipped Cao Gui as a doctor and married his daughter Cao Ji to Cao Gui.