In the eleventh year of King You of Zhou (771 BC), Hou Shen, the father of Queen Shen, was angry because King You of Zhou deposed his daughter Queen Shen and his grandson Yijiu, so he united with the Kingdom of Fu (now Nancheng, Henan) and the West Yi Quanrong launched a large-scale attack on Haojing, the capital of the Western Zhou Dynasty (today's Xi'an City, Shaanxi Province), defeated the elite Liudu Division of the Western Zhou Dynasty, and killed King You of Zhou at the foot of Lishan Mountain. Bao Si's whereabouts were unknown, and the Western Zhou Dynasty was destroyed. Extended information
Bao Si [bāo sì] (called "Xu Si" in "Historical Records", "Yu Si" in "Biography of Lienu"), unknown date of birth and death, surnamed Si, native of Bao country, King Ji Gongyuan of Zhou You The second queen, the biological mother of Prince Ji Bofu, and the stepmother of Zhou Ping Wang Ji Yijiu.
In 779 BC, King You of Zhou attacked Baoguo. Baoguo was defeated and offered Baosi to beg for surrender. After King Zhou You got praise from her, he doted on her very much. In 778 BC, Bao Si gave birth to a son, Ji Bofu, for King Zhou You. From then on, King Zhou You favored Bao Si even more, and finally deposed Queen Shen and Prince Ji Yijiu, and established Bao Si as queen and Ji Bofu as prince.
Bao Si didn't like to laugh by nature. In order to please Bao Si, King You of Zhou raised a beacon to summon the princes. The princes rushed there, but found that they were not invaded by bandits, so they had to retreat in embarrassment. In 771 BC, Hou Shen, the father of Queen Shen, joined forces with the state of Zu and the Quan Rong to attack King You of Zhou. King Zhou You raised a beacon to warn the princes, but the princes thought it was another scam and refused to go. As a result, King You of Zhou was killed by the Quan Rong, and Bao Si was also kidnapped. , and his whereabouts are unknown since then.
Reference: Baidu Encyclopedia-Bao Si