Qi State, at the beginning of its founding, was enfeoffed as a Marquis by the Son of Heaven of Zhou. This was not a very high status among the feudal states enfeoffed by the Son of Heaven of Zhou at that time.
Moreover, there were always powerful barbarians on the borders of the original Qi State. Therefore, during the reigns of its first few rulers, Qi was not a great power. Instead, states like Lu and Yan were far stronger than Qi.
At the end of the Shang Dynasty, Jiang Ziya assisted King Wu of Zhou in overthrowing the Shang and was enfeoffed to establish his state in the Qi region, naming it Qi.
Qi State appeared shortly after the establishment of the Zhou Dynasty. At that time, King Wu of Zhou, in order to reward his meritorious officials and the imperial clan, greatly implemented the enfeoffment system, first enfeoffing his teacher, the meritorious official Lu Shang, in Yingqiu, and naming the state Qi.
Taigong went east to take up his post. The neighboring Lai State's forces led by Lai Zi contended with Taigong for Yingqiu. After Taigong arrived in Yingqiu, he adapted to the local customs, simplified rituals, and reformed governance. He developed industry and commerce, utilized the local advantages of fish and salt, and his population increased greatly, making Qi a great state.
Although Qi State faced hostility from surrounding powers, from Jiang Ziya at the very beginning to the successive rulers, they all emphasized the development of commerce, and Qi State became the wealthiest state at that time.
The national strength of Qi State also grew accordingly.
After several generations of rulers, Qi State had become strong and was no longer restricted by other states. During the reign of King Wei of Qi, Qi State began to abandon its initial policy of focused development and started to frequently launch wars against external forces in pursuit of more territory.
Later, the Zhou royal family completely declined, the Zhou Dynasty perished, and wars between the feudal lords became more frequent. Qi State aggressively waged war in the north, attempting to replace the original influence of the Zhou royal family in the north.
King Wei of Qi dispatched heavy troops to fight against Lu, Yan, and Zhao, making all the feudal states and even the Son of Heaven wary.
However, not long after, a rebellion occurred within Qi. Tian Ji fell for a counter-espionage plot, attacked Linzi, and sought to seize Zou Ji. After being defeated, he fled to the state of Chu. It was not until King Xuan ascended the throne that he was recalled to the state to restore his former position.
This internal strife greatly weakened Qi State, but the rulers of Qi State still did not abandon their ambition for external conquest.
A few years later, the state of Yan experienced the "Rebellion of Zi Zhi." Under Mencius' persuasion, King Xuan of Qi ordered Kuang Zhang to lead the soldiers from the "five capitals" and the "northern populace" to destroy Yan in thirty days. However, Qi State did not achieve its goal this time.
The feudal lords jointly attacked Qi with heavy troops, and Qi State was forced to withdraw its forces.
This defeat caused Qi State to lose a large number of soldiers, and Qi State began to decline.
However, the rulers of Qi State still did not give up their plan to continue expanding their territory.
King Min of Qi ascended the throne and subsequently dispatched troops in continuous campaigns, conquering the state of Song, invading Wei to the south, and attacking Yan and Zhao to the west. The power of Qi State reached its peak, but crisis was also approaching.
Qi State did not properly govern the newly conquered territories, which led to numerous rebellions. However, King Min of Qi paid no attention, continuing to mobilize troops and increase taxes, plundering the populace.
Finally, King Zhao of Yan appointed Yue Yi as the supreme commander and allied with Yan, Yue, Lu, Han, Zhao, and Wei to attack Qi. They entered Linzi, capturing seventy-three cities in succession. Only Ju and Jimo remained unconquered.
Qi State managed to hold on for more than a decade with the support of Ju and Jimo, until King Zhao of Yan passed away and King Hui of Yan ascended the throne.
Tian Dan used a counter-espionage plot to get Yue Yi removed from his post. King Hui of Yan replaced Yue Yi with Qi Jie as the general, forcing Yue Yi to flee to the state of Zhao. Tian Dan organized a counter-offensive and defeated the Yan army with the "fire ox formation," recapturing lost territories and restoring the state in three months.
Although Qi State was restored, it was greatly weakened and could no longer participate in the struggle for hegemony.