Wu Chengsi

In spring 684, after Emperor Zhongzong showed signs of independence, she deposed him and replaced him with another son, Li Dan the Prince of Yu, but wielded power even more tightly thereafter.

He then had the commoner Tang Tongtai (唐同泰) "discover" the rock and offer it to Empress Dowager Wu as a sign of divine favor.

Empress Dowager Wu was very pleased and claimed herself the honorific title, "Holy Mother, the Divine and August One" (聖母神皇) and set a date to offer sacrifices to the god of Luo River, ordering the commandants, prefects, and nobles to be gathered at Luoyang for the sacrifices.

In 689, Empress Dowager made Wu Chengsi Nayan (納言) -- the head of examination bureau of government and a post considered one for a chancellor.

In 690, she made him Wenchang Zuo Xiang (文昌左相) -- one of the heads of the executive bureau of government, also considered a post for a chancellor.

However, Wu Zetian created Li Dan, the former Emperor Ruizong, crown prince (with the unconventional title Huang Si (皇嗣)).

The chancellors Cen Changqian and Ge Fuyuan opposed the movement and advocated that the petitioners be rebuked and disbanded—and their advocacy angered Wu Zetian.

Cen and Ge were soon arrested by her secret police official Lai Junchen, and soon, they, as well as another chancellor friendly to them, Ouyang Tong, were executed.

In 692, Lai falsely accused a group of individuals—the chancellors Ren Zhigu, Di Renjie, Pei Xingben, along with the other officials Cui Xuanli (崔宣禮), Lu Xian (盧獻), Wei Yuanzhong, and Li Sizhen (李嗣真) of treason.

These officials, in order to avoid torture, confessed to treason—but managed to escape death when Di wrote a secret plea and hid it inside blankets to be smuggled out to his family members, who presented it to Wu Zetian, who then spared them from death but exiled them, despite Lai's and Wu Chengsi's advocacy that they be killed.

Wu Chengsi invited Biyu to come to his mansion to teach his own concubine arts, and then kept her and would not allow her to go back to Qiao.

In 701, Wu Yanji was accused of privately discussing the Zhangs and his execution ordered along with that of his brother-in-law Li Chongrun, Prince of Shao and eldest son of Emperor Zhongzong.