Count Ji Chang ruled for fifty years but passed away before he could complete his grand plan to overthrow the Shang Dynasty. Although he never launched an actual attack against the Shang during his lifetime, with the assistance of Jiang Shang, he laid a solid foundation for his descendants to overthrow Shang rule. After his death, Ji Chang was posthumously honored as King Wen, and his son Ji Fa succeeded him, becoming King Wu of Zhou. King Wu carried on his father's legacy and actively prepared for an offensive against the Shang. To facilitate the attack on the Shang capital of Zhaoge, he also moved the capital from Feng to Hao.
At this time, under the rule of the tyrannical King Zhou, the Shang Dynasty's government had become extremely corrupt. To test the Shang's military strength and gauge the realm's reaction to an attack on the Shang, King Wu, in the second year of his reign, under the pretext of honoring King Wen, led a large army westward to the tomb of King Wen at Biyuan (present-day Chang'an, Shaanxi), then turned eastward toward Zhaoge, arriving at Mengjin on the southern bank of the Yellow River (northeast of present-day Mengjin, Henan). King Wu proclaimed himself as Crown Prince Fa and erected a large wooden placard bearing his father Xibo Chang's name in the army, signifying that King Wen remained the supreme commander. Over eight hundred lords, upon hearing the news, came to join the alliance. At the assembly, King Wu held a swearing-in ceremony and issued an oath, with the lords urging him to immediately attack Zhaoge. However, King Wu and Jiang Taigong believed that the Shang's military strength should not be underestimated and that the time to attack had not yet come. Thus, King Wu admonished everyone to "wait for the mandate of heaven" and ordered the entire army to cross the Yellow River and return westward, biding their time. This was the historically famous "Mengjin Military Review," through which King Wu observed that the people's hearts were turning to Zhou, while King Zhou of Shang had become isolated and abandoned.
Just as the crisis on the western front of the Shang Dynasty eased, the Dongyi took the opportunity to launch a large-scale attack on Shang. King Zhou assembled heavy forces and launched an offensive against the Dongyi. The battle between the two sides was fierce. The Dongyi were brave and skilled archers, but the Shang army was well-equipped, with weapons made of bronze that were exquisite, sharp, and highly lethal. Moreover, during the battle, the Shang army even organized elephant units to fight, as recorded in ancient texts: "The Shang people used elephants to oppress the Dongyi." The Shang army held a decisive advantage in the battle, as wave after wave of Dongyi soldiers fell, and many Yi people were captured and reduced to slavery.
King Zhou of Shang led the Shang army to press forward with unstoppable momentum, charging all the way to the lower reaches of the Yangtze River, subduing most of the Dongyi tribes and capturing tens of thousands of Dongyi people. To permanently eliminate future threats, King Zhou even built a grand road leading to the Dongyi region, allowing for rapid troop deployment to suppress any uprising. From then on, the Central Plains and the southeastern regions were connected, strengthening ties between the central and southeastern areas and enabling Shang culture to spread widely throughout the Yangtze River basin in the southeast. With its superior natural geographical conditions and the local people's adoption of advanced agricultural civilization, the region developed very rapidly.
However, this campaign dragged on for a long time, and the constant conscription of troops increased the burden on the people, severely draining the Shang Dynasty's strength and hastening its downfall. This is why the Zuo Commentary records the saying, "King Zhou of Shang conquered the Eastern Yi but brought about his own ruin."
According to the Zuo Zhuan (Zuo Commentary), King Zhou of Shang likely captured Daji from the Yousu tribe during his campaign against the Dongyi. After acquiring Daji, he doted on her excessively. Despite years of warfare draining the state's resources, he grew complacent and indulged in luxury and debauchery, building the Deer Terrace and instituting the cruel punishment of branding on a heated bronze pillar. The virtuous ministers Bi Gan and Ji Zi offered loyal remonstrations—one was killed, the other imprisoned. Seeing that King Zhou was beyond redemption, the Grand Tutor and Junior Tutor fled Chaoge with the ancestral sacrificial vessels of the Shang dynasty, further intensifying internal conflicts within the Shang court.
King Wu and Jiang Shang believed the time had come to launch their campaign. Thus, King Wu announced to all the feudal states his decisive decision to march on Zhaoge, the capital of the Shang Dynasty, for the final battle to overthrow the Yin.
Around 1046 BCE, King Wu of Zhou led 300 war chariots, 3,000 guards, and 45,000 infantry across the Yellow River at Mengjin, arriving at Muye (south of present-day Weihui, Henan), 70 li from the Shang capital Zhaoge, where he joined forces with 4,000 chariots from allied states including Yong, Shu, Qiang, Wei, Lu, Peng, and Pu.
Before the battle, King Wu held a rally to address the entire army, delivering a speech known as the "Oath at Muye" from the Book of Documents. In the oath, he listed King Zhou's crimes, such as heeding only the words of his consort Daji and betraying his ancestors, declaring that the campaign against Zhou was carried out in accordance with "the will of Heaven." He also instructed the soldiers to maintain strict discipline and fight bravely in battle.
By the time King Wu of Zhou's massive army had already arrived at the outskirts of Zhaoge, King Zhou of Shang finally woke up to the crisis, hastily stopping his feasts of song and dance to summon his ministers for counsel. At that moment, the main forces of King Zhou's army were stationed elsewhere, leaving the city's defenses severely undermanned. Forced into a corner, King Zhou armed prisoners, slaves, and captives, scraping together 170,000 men to march toward Muye for a hasty battle.
The two sides engaged in a decisive battle at Muye, where the Zhou army fought with high morale and fierce charges, while the Shang army was demoralized and lacked any will to fight. King Wu exploited the people's resentment and dissatisfaction toward King Zhou of Shang, inciting the soldiers to revolt. As a result, the hastily assembled Shang army turned their weapons against their own side at the front lines, opening a path for King Wu's forces to storm into Chaoge. This is the famous "Battle of Muye."
King Zhou of Shang, seeing that the situation was hopeless, retreated overnight to Zhaoge, ascended the Deer Terrace, and set himself on fire, dying in the flames. King Wu of Zhou completely occupied the Shang capital, and thus the Shang Dynasty came to an end. Afterward, King Wu established the Zhou Dynasty, which history records as the "Western Zhou."