Duke Xiao's father was
Duke Huan of Qi, who was the first of the
Five Hegemons, the most powerful rulers of the
Spring and Autumn period. Duke Huan had at least three main wives who bore no sons, six favoured concubines, and more than ten sons. Duke Xiao was then known as Crown Prince Zhao, and his mother was Zheng Ji, a princess of the
State of Zheng. Five other sons of Duke Huan also contended for the throne: Prince
Wukui, Prince Pan (later
Duke Zhao), Prince Shangren (later
Duke Yi), Prince Yuan (later
Duke Hui), and Prince Yong. When Duke Huan died in the tenth month of 643 BC, the six princes
fought each other for the throne. After two months of fighting Wukui prevailed and ascended the throne in the twelfth month. Crown Prince Zhao fled to the
State of Song. During the unrest Duke Huan's corpse lay unattended for 67 days, and it was so badly decomposed that worms crawled out of his room. Wukui sat on the throne for only three months before being killed. In the third month of 642 BC, Prince Zhao returned with the army of
Duke Xiang of Song. The people of Qi killed Wukui and wanted to install Prince Zhao on the throne, but the supporters of the other four princes attacked and drove Prince Zhao back to the State of Song. Two months later, the Song army returned and defeated the forces of the four princes, and Prince Zhao finally ascended the throne, to be known as Duke Xiao of Qi. ==Reign==