Zhou–Chu War

The Zhou–Chu War was a military conflict between the Zhou dynasty under King Zhao and the state of Chu from 961 to 957 BC. King Zhao personally led at least two major campaigns against Chu and other states and tribes of the middle Yangtze region, initially conquering the lands north of the Yangtze and the Han River valley. Eventually, however, the Zhou forces suffered a crushing defeat, with half of their armed forces as well as King Zhao killed, subsequently losing control of much conquered territory. The war ended the era of Western Zhou’s early expansion and forced it into the defense against foreign aggressors. On the other side, Chu consolidated its de facto independence and would continue to grow into one of the most powerful states of China.

Prelude


After suppressing the Rebellion of the Three Guards, the Zhou dynasty entered an era of stability and territorial expansion. Under the rule of King Cheng the kingdom used its growing military strength to conquer and colonize western Shandong and the land north of the Huai River. His successor, King Kang, led victorious campaigns against the Guifang of Shanxi and northern Shaanxi, while continuing the war against the Dongyi of eastern Shandong. During the reign of King Zhao, however, the Zhou court's focus shifted from the east and north to the middle Yangtze region.

This region had a longer history of bronze culture and state building than the Dongyi, and was thus economically, technologically and politically more advanced. It was also extremely rich in ores like copper and tin that were badly needed for the large-scale bronze production of the Zhou dynasty, as well as gold. As result, northern states had long attempted to gain control of the southern mines. The Shang dynasty had heavily relied on the middle Yangtze deposits since the late Erligang period, and subsequently established several bases (such as Panlongcheng) in the region. After the fall of the Shang, the expansionist state of Chu, whose rulers claimed descent from the legendary northern Xia dynasty, had emerged as the most powerful polity of the middle Yangtze region. Formed as indigenous tribal confederation influenced by northern culture, Chu had already existed during the late Shang dynasty and ruled over several minor vassal states and tribes.

Before King Zhao's reign Chu and Zhou had a long history of cooperation. The Chu confederation under Yuxiong allegedly assisted the Zhou during their conquest of the Shang dynasty. The next known Chu ruler, Xiong Yi, submitted to King Cheng, who in turn enfeoffed him as viscount. Under King Kang, Xiong Yi even became one of the five most important ministers at the Zhou court. Meanwhile, Chu rapidly expanded and possibly united the Han River and the middle Yangtze valleys under its control. Chu’s expansion, coupled with the Zhou dynasty’s demand for the south’s mineral wealth, and a desire to retake the territory that the Shang dynasty had once controlled, eventually led to the deterioration of the relationship between the two polities. As result, the Chu rulers might have begun to title themselves kings in open defiance of the Zhou monarchs. Due to their technological and military power Chu could also raise a much more formidable resistance than any other polity that the Zhou kingdom had faced before. Furthermore, the middle Yangtze region was not well suited for the Zhou military, as it was dominated by marches, swamps, and mountains that greatly hindered traditional troop movements.

War
The war began around 961 BC, in the sixteenth year of King Zhao's reign, when either one of the Chu vassal states attacked Zhou territory or Zhao launched a preemptive strike. As hostilities broke out, Zhou official Bo Meifu was ordered to patrol the Han River, while the southern Zhou vassal states of Zeng, E, Fang, and Deng were inspected and enlisted for the war effort. When the Zhou royal forces arrived from Chengzhou in the middle Yangtze region, they set up their camp at Zeng. From there, they attacked and initially subdued the 26 states of the Han River valley which had been under Chu's control. King Zhao captured much loot, especially precious metals, supporting the theory that one major reason for Zhou’s southern expansion was the quest for ores. The king was unable to or chose not to destroy or occupy Chu, however, so that Chu was able to rebuild its strength. Nevertheless, the Zhou forces managed to take full control of the area east of the Han River and north of the Yangtze. There, they constructed the stronghold of Lutaishan as political and military base.

After three years, King Zhao launched another major military campaign beyond the Han River. As he employed half of Zhou's royal forces, organized into the "Six Armies of the West", Li Feng believes that this massive assault indicated Zhao's desire to permanently bring the middle Yangzi region under his control. This campaign, however, ended in disaster for Zhou as their armies were routed and, along with King Zhao, drowned in the Han River. Yin Hongbing assumes that the unfamiliarity of the Zhou with the geographical and climatic features of the south led to their eventual defeat.

Aftermath


King Zhao’s disastrous defeat had serious political repercussions for the Zhou dynasty. The destruction of nearly half of the royal forces, possibly over 75,000 soldiers, was an overwhelming military setback. It stopped the Zhou kingdom’s expansion and forced it into the defense, as the Zhou attempted to rebuild their strength. There were no more serious invasions of the southern polities, and the Zhou were therefore never again able to venture farther south into the middle Yangtze region. Military campaigns against the Dongyi of Shandong stagnated and then ceased altogether. However, despite his “humiliating end”, King Zhao was still sometimes commemorated for his southern campaigns, as he had at least established political dominance over the region to the north of the Yangtze and east of the Han River. The Zhou were also able to rebuild the lost Six Armies of the West during the reign of Zhao’s successor, King Mu, and successfully defended the kingdom against ensuing foreign invasions.

That these invasions even occurred, however, is a sign for the decline of the Western Zhou. Much more serious than its military losses was the far-reaching psychological impact of the Zhou defeat. For the Zhou people there could have hardly been a worse omen than the inauspicious death of the Son of Heaven at the hands of the southern barbarians. The Zhou kingdom was no longer invincible, and from then on its enemies “would not hesitate to test its strength whenever possible.” The Zhou state "never really recovered from this loss". Under the following kings, revolts of vassal states and foreign invasions of Zhou lands became ever more frequent.

Meanwhile, the Chu confederation nominally submitted once again to the Zhou kings after its victory, with its rulers refraining from using royal titles. As Chu had firmly established its autonomy and control over the middle Yangtze region, there was no longer any need to openly defy the Zhou monarchs. Following his father's death, King Mu led a punitive campaign against the confederation to force it back into full submission, but was unsuccessful. Chu remained unchallenged and virtually independent. Possibly to check the confederation's expansion, the Zhou dynasty moved its vassal state of E into the Nanyang Basin, north of Chu. Until the rule of King Li of Zhou, E was possibly the most powerful state of the middle Yangzte region, and ensured Zhou's security in the south. E revolted in 850 BC, however, and was destroyed by Zhou, allowing it to be absorbed by Chu which consequently grew even more powerful. After one last war with Zhou in 823 BC, the state of Chu fully seceded from the Zhou kingdom. After 703 BC, the Chu rulers finally declared themselves kings and equals to the Zhou rulers.