Duke Huan of Qi unites all the lords in nine

Although Qi had lost a battle at Chang Spoon, this did not affect the later hegemony of Duke Huan of Qi. After more than ten years, the northern state of Yan (with its capital in present-day Beijing) sent messengers to ask for help, saying that Yan had been invaded by a nearby tribe, the Shandong, and had lost a battle. Duke Huan of Qi then decided to lead a large army to rescue Yan.

In 663 B.C., when the Qi army arrived at Yan, Shandong had already robbed a group of people and treasures and fled back.

The armies of Qi and Yan united and kept chasing northward. Unexpectedly they were led into a lost valley by the enemy. The lost valley was like an ocean, with no boundaries and no way to find the original path.

But Guan Zhong came up with an idea. He said to Duke Huan of Qi, "The horses may know the way, so why don't we find some old local horses and let them walk in the head, maybe they can get out of this place."

The Duke of Qi Huan had some old horses picked out and asked them to lead the way. These old horses did lead the people out of the lost valley.

After Duke Huan of Qi helped Yan to defeat Shan Rong, Xing was also invaded by another tribe, the Di. The Duke of Qi Huan took his men and horses to chase away the Di and helped Xing to rebuild its city walls. Next, the Di invaded the State of Wei, and Duke Huan of Qi helped Wei rebuild its capital on the south bank of the Yellow River. Because of these few events, the prestige of Duke Huan of Qi increased. Only the southern state of Chu (whose capital was northwest of Jiangling in present-day Hubei) not only disobeyed Qi but also opposed it and wanted to compete with it.

The state of Chu was in the south of China and had never had any dealings with the lords of the Central Plains. At that time, the lords of the Central Plains treated Chu as "barbarians". However, the Chu people reclaimed the land in the south and gradually conquered some nearby tribes, and slowly became a great power. Later, they simply called themselves the kings of Chu, ignoring the emperor of the Zhou Dynasty.

In 656 B.C., Duke Huan of Qi appointed the armies of Song, Lu, Chen, Wei, Zheng, Cao, and Xu to jointly attack the state of Chu.

When King Cheng of Chu learned of the news, he also gathered his men and horses to prepare for resistance. He sent a messenger to the Duke of Qi and said, "Our king asked me to ask you, "Qi is in the north and Chu is in the south, and the two countries do not communicate with each other. Why do your soldiers and horses come here?"

Guan Zhong rebuked, "Although our two countries are far apart, both of them were enfeoffed by the Son of Zhou. At the time when the Duke of Qi was enfeoffed, he received an order that if anyone disobeyed the Son of Heaven, Qi had the right to conquer. You in Chu used to pay tribute to the Son of Heaven every year for the bao mao (a kind of green mao used to filter wine), why don't you pay tribute now?" The ambassador said, "It is our fault that we did not pay the tribute to Baomao, but we will do so in the future."

After the messenger left, the allied army of Qi and the vassals again drew up their camp and advanced until they reached Zhaoling