Around the year 1046 BCE, King Wu, of the province of Zhou, rebelled against King Zhou of Shang and defeated his forces at the Battle of Muye, establishing the Zhou Dynasty (c. 1046- 256 BCE). 1046-771 BCE marks the Western Zhou Period while 771-226 BCE marks the Eastern Zhou Period. The Mandate of Heaven was invoked by the Duke of Zhou, King Wu's younger brother, to legitimize the revolt as he felt the Shang were no longer acting in the interests of the people.
The Mandate of Heaven was thus defined as the gods' blessing on a just ruler and rule by divine mandate. When the government no longer served the will of the gods, that government would be overthrown. Further, it was stipulated that there could be only one legitimate ruler of China and that his rule should be legitimized by his proper conduct as a steward of the lands entrusted him by heaven. Rule could be passed from father to son but only if the child possessed the necessary virtue to rule. This mandate would later be often manipulated by various rulers entrusting succession to unworthy progeny.
Under the Zhou, culture flourished and civilization spread. Writing was codified and iron metallurgy became increasingly sophisticated. The greatest and best known Chinese philosophers and poets, Confucius, Mencius, Mo Ti (Mot Zu), Lao-Tzu, Tao Chien, and the military strategist Sun-Tzu (if he existed as depicted), all come from the Zhou period in China and the time of the Hundred Schools of Thought.
The chariot, which was introduced to the land under the Shang, became more fully developed by the Zhou. It should be noted that these periods and dynasties did not begin nor end as neatly as they seem to in history books and the Zhou Dynasty shared many qualities with the Shang (including language and religion). While historians find it necessary, for clarity's sake, to break events into periods, the Zhou Dynasty remained extant through the following recognized periods known as The Spring and Autumn Period and The Warring States Period.
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The Spring & Autumn Period & The Warring States
During the Spring and Autumn Period (772-476 BCE and so called from the Spring and Autumn Annals, the official chronicle of the state at the time and an early source mentioning General Sun-Tzu), the Zhou government became decentralized in their move to the new capital at Luoyang, marking the end of the `Western Zhou' period and the beginning of `Eastern Zhou'. This is the period most noted for advances in philosophy, poetry, and the arts and saw the rise of Confucian, Taoist, and Mohist thought.
At the same time, however, the different states were breaking away from central rule by Luoyang and proclaiming themselves sovereign. This, then, led to the so-called Warring States Period (476-221 BCE) in which seven states fought with each other for control. The seven states were Chu, Han, Qi, Qin, Wei, Yan, and Zhao all of whom considered themselves sovereign but none of whom felt confident in claiming the Mandate of Heaven still held by the Zhou of Luoyang. All seven of the states used the same tactics and observed the same rules of conduct in battle and so none could gain the advantage over the others.
This situation was exploited by the pacifist philosopher Mo Ti, a skilled engineer, who made it his mission to provide each state with equal knowledge of fortifications and siege ladders in hopes of neutralizing any one state's advantage and so ending the war. His efforts were unsuccessful however and, between 262 and 260 BCE, the state of Qin gained supremacy over Zhao, finally defeating them at The Battle of Changping.
A Qin statesman by the name of Shang Yang (died 338 BCE), a great believer in efficiency and law, had re-cast the Qin understanding of warfare to focus on victory at any cost. Whether Sun-Tzu or Shang Yang is to be credited with reformation of military protocol and strategy in China depends on one's acceptance of Sun-Tzu's historicity. Whether Sun-Tzu existed as people claim, however, it is very probable that Shang Yang was acquainted with the famous work, The Art of War, which bears Sun-Tzu's name as author.
Prior to these reforms, warfare was considered a nobleman's game of skill with very set rules dictated by courtesy and the perceived will of heaven. One did not attack the weak or the unprepared and one was expected to delay engagement until an opponent had mobilized and formed ranks on the field. Shang advocated total war in pursuit of victory and counselled taking the enemies' forces by whatever means lay at hand. Shang's principles were known in Qin, and made use of at Changping (where over 450,000 captured Zhao soldiers were executed after the battle) giving the Qin the advantage they had been waiting for.
Still, they did not make further effective use of these tactics until the rise of Ying Zheng, King of Qin. Utilizing Shang's directives, and with an army of considerable size using iron weapons and driving chariots, Ying Zheng emerged from the Warring States conflict supreme in 221 BCE, subduing and unifying the other six states under his rule and proclaiming himself Shi Huangdi -`First Emperor' - of China.