He assumed the throne after his father, Duke Huan of Zheng, was killed alongside King You of Zhou in a 771 BC Quanrong attack on the Western Zhou capital Haojing.
Duke Wu later annexed the states of Eastern Guo (東虢), Hu (胡), Kuai (鄶), and Ji (祭).
Despite his wife's (Wu Jiang's) requests, Duke Wu did not make his younger son, Gongshu Duan, his heir; he instead favored Wusheng, the future Duke Zhuang.
[3] Additionally, he made Duan the ruler of Jing, Zheng's capital.
[2] These factors caused Duan to rebel against Duke Zhuang after their father's death.