In 555 BCE, the State of Qi launched an attack on the State of Lu, prompting Duke Xiang of Lu to send an urgent plea for help to the State of Jin. Duke Ping of Jin swiftly rallied the rulers of twelve allied states, including Zheng, Song, Wei, and Cao, to march against Qi and rescue Lu. They crushed the Qi army in a decisive battle and pursued the remnants all the way to the Qi capital, Linzi, laying siege to the city and trapping it completely.
At that moment, two senior officials of the Zheng state, Gongsun Shezhi and Gongsun Xia, secretly sent a letter to Duke Jian of Zheng, warning that another minister, Gongzi Jia, was plotting rebellion and had colluded with the Chu army to attack Zheng. The letter urged, "The Chu forces are already on the march—Your Grace must lead the army back immediately to defend the capital."
Duke Jian of Zheng immediately reported this to Duke Ping of Jin, who summoned his chief military commander, Zhongzhu Yan, to discuss the matter together.
Zhongzhu Yan said, "Your Majesty, although we have surrounded Linzi, its walls are high and sturdy, and the Qi army is prepared. We may not breach it quickly. If Chu captures Zheng, the blame falls on Jin. We should lift the siege and return to save Zheng!"
Duke Ping of Jin agreed, so he ordered Duke Jian of Zheng to lead his troops back to Zheng first, while he himself commanded the allied forces of eleven states to march out afterward.
A few days later, the army arrived at Zhu'a (southwest of present-day Licheng, Shandong). Duke Ping of Jin, knowing the Chu army was formidable and the outcome uncertain, felt deeply troubled. The court musician Shi Kuang played the zither to cheer him up. When finished, Shi Kuang said to Duke Ping of Jin:
"Your Majesty need not worry. When I played the zither just now, the north wind was clear and gentle, while the south wind was weak and low, lifeless and sluggish. In this campaign, Chu's army will surely toil without success. Within three days, good news will certainly arrive."
Duke Ping of Jin, still skeptical, sent scouts to Zheng to verify the news. Within three days, Zheng's Grand Master Gongsun Dun arrived to report, "The Chu army has withdrawn, and the rebellious minister Gongzi Jia has been executed."
Prince Jia had originally planned to coordinate with the Chu army from within, but once Gongsun Shezhi and Gongsun Xia learned of his plot, they tightened their defenses. Meanwhile, Duke Jian of Zheng rushed back with his troops. As the Chu army crossed into Zheng territory, they were hit by a blizzard—freezing cold and heavy snow killed many soldiers. With no word from Prince Jia as their inside man, the Chu forces had no choice but to retreat.
Duke Ping of Jin was overjoyed and deeply impressed by Shi Kuang's ability to deduce the outcome of war from the sound of music. He then informed the various feudal lords of the situation, and together they withdrew their troops and returned to their states.
Later, the idiom "Southern Wind Fails to Prevail" came to be used to describe a side's losing trend in battle.
Source: *Zuo Zhuan*, "The Eighteenth Year of Duke Xiang"
Meaning of the Idiom: Later, the Chinese idiom "南风不竞" came to describe a sides losing trend in battle.