Zhou Wuwang 周武王, King Wu of Zhou, personal name Ji Fa 姬發, was the founder of the Zhou dynasty (11th cent.-221 BCE). He was the son of Ji Chang 姬昌, Viscount of the West 西伯, posthumously called King Wen of Zhou 周文王.
When he became head of the house of Zhou, Ji Fa moved the residence from Feng 豐 to Hao 鎬, called Zongzhou 宗周 (near modern Xi'an 西安, Shaanxi). He inherited from his fathers a handfull of competent counsellors, like Duke Taigong Wang 太公望 (Jiang Ziya 姜子牙), Dan, the Duke of Zhou 周公旦, Shi, the Duke of Shao 召公奭, San Yi Sheng 散宜生, Tai Dian 太顛, or Hong Yao 閎夭.
In the second year of his "reign", his army encountered the royal army of Shang at Mengjin 盟津. Although Ji Fa had a large army of his own and that of many allies at disposal, he refrained from destroying the army of Shang, because he believed that time was not ripe yet. King Zhou's son Weizi 微子 fled the royal court after he had remonstrated against the king's cruel government in vain.
Bi Gan 比干, his uncle, was killed by King Zhou. Only then, Ji Fa decided to attack the royal army. With the troops of numerous allies from the west, Yong 庸, Shu 蜀, Qiang 羌, Wu 髳, Wei 微, Lu 盧, Peng 彭, and Pu 濮, he crossed the Yellow River at Mengjin, met the regional rulers (zhuhou 諸侯) and made his Great Speech (Taishi 太誓) that is also recorded in the history Shangshu 尚書 "Book of Documents".
On an auspicious day, the armies met at Muye 牧野, not far from the royal residence， where Ji Fa made his famous speech of Muye (Mushi 牧誓). He defeated the royal army, and King Zhou of Shang, recognizing that his rule was come to an end, burned himself on the Lutai Terrace 鹿臺 (or Nandan Terrace 南單臺).
Ji Fa thus ended the Shang dynasty and took over regency as king of Zhou. He divided the royal domain into three territories of supervision (sanjian 三監) to control the former royal domain of the Shang. The state of Bei 邶 was bestowed upon Lu Fu 祿父 (also called Wu Geng 武庚,the son of the late King Zhou of Shang), Yong 鄘 to his own brother Guan Shu 管叔, and Wei 衛 to his brother Cai Shu 蔡叔 (one source says, to Guan Shu, Cai Shu and Huo Shu 霍叔).
King Wu also dispatched his armies to subdue the last nobles refusing to accept him as the new king. He divided the whole land into states, the most important of which he gave into the hands of his kinsmen and the most loyal comrades. Duke Taigong was bestowed with Qi 齊, Ji Fa's uncle, the Duke of Shao, with Yan 燕, and the other uncle, the Duke of Zhou, with Lu 魯. Many other states could stay in the hands of lords who had changed sides from Shang to Zhou, like Jiao 焦, Zhu 祝, Ji 薊, Chen 陳, or Qi 杞.
In order to have a tighter control on the Yellow River plain, he planned to establish a secondary capital at Luoyi 雒邑 (modern Luoyang 洛陽, Henan), but he died before the construction was begun.
Ji Fa was given the dynastic title of King Wu "the Martial". His successor was his son Ji Song 姬誦, known as King Cheng of Zhou 周成王.