因势利导 — “Follow the trend and guide skillfully”

During the Warring States period, Sun Bin and Pang Juan, both from the state of Qi and Wei respectively, studied military strategy under Guiguzi. Later, Pang Juan became a grand general in the state of Wei. Out of jealousy for Sun Bin's superior talents, he had Sun Bin's legs amputated and his face tattooed and smeared with ink.

Subsequently, Sun Bin became a military advisor for the state of Qi, assisting General Tian Ji in leading an army of 50,000 to attack Wei and rescue Han. Following Tian Ji's suggestion, Sun Bin directed the army to launch an attack on Daliang, the capital of Wei, forcing Pang Juan to withdraw his troops from Han. As expected, Pang Juan, upon hearing the news, hastily retreated his army from Han. By this time, the Qi army had already entered Wei.

Sun Bin then told Tian Ji, "The Wei army has always been known for its ferocity and arrogance; they do not regard our Qi army highly. A skilled military strategist must understand the meaning of 'yin shi li dao' – to follow the prevailing trends of the enemy's thinking and skillfully guide them into a trap." Following this principle, Sun Bin ordered the number of cooking stoves to be reduced daily, creating a false impression of large-scale desertions in the Qi army. Pang Juan indeed fell into the trap. He left his infantry behind and pursued with only his elite troops.

Sun Bin set up an ambush at Maling, and on a tree, he inscribed the words: "Pang Juan will die under this tree." When Pang Juan arrived at Maling, he tried to light a fire to read the inscription on the tree. Suddenly, the Qi army launched a barrage of arrows. The Wei army suffered heavy casualties, and Pang Juan was struck by six arrows. Facing utter defeat, he had no choice but to draw his sword and commit suicide.

It is worth noting that the protagonist, Sun Bin, was not originally named Sun Bin but acquired this name after undergoing the 'bin' punishment (amputation of the legs).