In 597 BCE, the state of Chu launched an attack on Zheng, a small and weak state unable to withstand Chu's forces. To protect his kingdom, Duke Xiang of Zheng led his troops in resistance while sending messengers to their ally, the state of Jin, for reinforcements.
The armies of Zheng and Chu had been locked in brutal combat for three or four months, and Zheng was gradually losing ground to Chu's relentless assault. Seizing the moment before reinforcements from Jin could arrive, Chu forces stormed and captured Zheng's capital, Xingyang.
To save his life, Duke Xiang of Zheng personally went to King Zhuang of Chu to apologize and offered to form an alliance. To earn the king's trust, he left his younger brother and son as hostages. King Zhuang accepted the alliance and then led his army back home.
After the Chu army returned home, Duke Xiang of Zheng discovered that the Jin relief forces had arrived between Mount Ao and Mount Hao northwest of Xingyang, and this time Jin had dispatched six hundred war chariots under the command of the renowned Marshal Xun Linfu, making their presence formidable. Duke Xiang of Zheng, fearing that Jin would rebuke him for abandoning their alliance to side with Chu, grew deeply anxious.
Duke Xiang then summoned his ministers to discuss a plan. Grandee Huang Shu said, "At this point, we must let the Jin and Chu armies fight it out. Whoever wins, we will ally with them. Your Majesty, leave this matter to me!"
Duke Xiang agreed. Huang Shu then went to the Jin camp to meet the Jin commander Xun Linfu and explained, "Zheng's alliance with Chu had no other motive—it was only to preserve the state of Zheng. Please understand."
Huang Shu added, "The Chu army, returning in triumph, is sure to be arrogant and complacent. If Jin attacks now, they will catch them off guard. With Zheng backing them, they will surely defeat Chu."
Xun Linfu, momentarily at a loss, told the man to rest while he gathered his generals for counsel.
Deputy Commander Xian Gu said, "Since Zheng has allied with us, now that they are in trouble, we should agree to their request and help them defeat Chu."
The deputy commander of the lower army, Luan Shu, disagreed, saying, "The Chu army is not to be underestimated. Since the founding of Chu, its rulers have constantly reminded the people of life's hardships and maintained strict military discipline. The people and soldiers are always in a state of readiness. Moreover, Chu's former rulers, Ruo'ao and Fenmao, wore tattered clothes and rode in crude carts to develop the wilderness. They led by example, teaching the people the virtue of hard work. This hardly shows arrogance."
The generals argued back and forth, each offering a different opinion, leaving Xun Linfu unsure whose advice to follow.
Xian Gu, the impetuous deputy commander of the central army, took it upon himself to lead his troops in pursuit of the retreating Chu forces. Caught off guard during their withdrawal, the Chu army was suddenly attacked. King Zhuang of Chu had no desire to fight, but yielding to the demands of his generals, he ordered a counterattack. The Jin army, completely unprepared, was routed and suffered a crushing defeat.
This was the famous Battle of Bi in history, from which point Chu replaced Jin as the dominant power.
Later, people used the idiom "Bilu Lanlu" to describe the hardships of starting a business.
Source: *Zuo Zhuan*, "Duke Xuan's Twelfth Year"
Meaning of the Idiom: Later, the Chinese idiom "筚路蓝缕" came to describe the hardships of starting a business.