Emperor Ruizong, however, was a hollow figurehead under control of his mother and had no real power, even nominally, his name was not included in the issued documents or orders.

From then onwards, the Tang dynasty existed only in name and Empress Dowager Wu ruled China for over six years as quasi-emperor.

Empress Wu, was comfortable about the empire being entirely under her control, decided finally to seize the throne, so in October 690 Emperor Ruizong ceded the imperial throne to his mother, who installed herself as empress regnant – the only woman in Chinese history ever to rule with this title.

[note 1] Emperor Ruizong was reduced to the position of crown prince, with the unconventional title of Huangsi (皇嗣, "imperial successor").

Eventually, in October 698, faced with foreign invasion and dissatisfaction at home, Empress Wu accepted the suggestion of the chancellor Di Renjie and recalled the exiled Li Xian to the capital Luoyang.

Soon, however, tensions mounted between Princess Taiping, who had immense power, complete trust of the emperor and many supporters, and Li Longji (who was created crown prince).

This allowed Princess Taiping to continue to participate and have influence in governmental affairs without change and still had the power to stubbornly resist and bitterly fight against Li Longji (now Emperor Xuanzong).

Eventually, in 713, suspecting Princess Taiping of planning a coup, Emperor Xuanzong acted first, killing her associates and forcing her to commit suicide.

Soon after Emperor Ruizong took the throne, Empress Dowager Wu carried out a major renaming of governmental offices and banners.

She further, at the suggestion of her nephew Wu Chengsi, built an ancestral temple for five generations of her ancestors and had Emperor Ruizong posthumously create them princes.

In 686, Empress Dowager created a number of bronze boxes designed to encourage secret reports of crimes.

She also began to retain a group of secret police officials to carry out torture and interrogation of people suspected of opposing her rule, including Suo Yuanli, Zhou Xing, and Lai Junchen.

Emperor Ruizong had completely stayed out of political matters during these years, but he made an exception in 687 when Empress Dowager Wu believed the chancellor Liu Yizhi, who had previously served on his staff when he was a prince, whom she had trusted and promoted, to have turned against her in favoring that she return imperial authorities to Emperor Ruizong.

In 688, fearing that Empress Dowager Wu was using a ceremony to worship the god of the Luo River (洛水, flowing near Luoyang) as an excuse to summon them to Luoyang to slaughter them, the imperial princes considered rebellion, and one was launched by Emperor Ruizong's uncle Li Zhen the Prince of Yue and Li Zhen's son Li Chong the Prince of Langye, claiming that Emperor Ruizong was under arrest and needed to be rescued.

She demoted Emperor Ruizong to the position of crown prince (with the unusual title Huangsi (皇嗣)), and changed his name back to Lun.

Meanwhile, in 693, Wu Zetian's lady in waiting Wei Tuan'er (韋團兒), who was resentful of Li Dan for reasons lost to history, falsely accused Li Dan's wife Crown Princess Liu and concubine Consort Dou of witchcraft, and Wu Zetian killed Crown Princess Liu and Consort Dou.

Wu Zetian ordered that the officials not be allowed to meet Li Dan, and further arrested his servants to interrogate them.

In 705, Wu Zetian was overthrown in a coup led by Zhang Jianzhi, Cui Xuanwei, Huan Yanfan, Jing Hui, and Yuan Shuji.

Emperor Zhongzong also gave Li Dan the title of Taiwei (太尉, one of the Three Excellencies) and made him a chancellor with the designation of Tong Zhongshu Menxia Sanpin (同中書門下三品).

After Li Chongmao took the throne (as Emperor Shang), Empress Wei became empress dowager and regent, while Li Dan only received an entirely ceremonial title of senior advisor to the crown prince (太子太師, Taizi Taishi) – as there was no crown prince at the time.

Meanwhile, Empress Dowager Wei's party viewed Li Dan and Princess Taiping as threats and considered eliminating them.

Li Longji responded by conspiring with Princess Taiping, Princess Taiping's son Xue Chongjian (薛崇簡), as well as several low-level officials close to him – Zhong Shaojing, Wang Chongye (王崇曄), Liu Youqiu, and Ma Sizong (麻嗣宗) – to act first.

Meanwhile, though, with Emperor Ruizong considered meek, the court was dominated by two competing factions—of Princess Taiping and Li Longji.

Among the relatives of the Tang dynasty and the ministers of civil and military affairs, there was still one person who made her feel terrified, and that was Li Longji.

Meanwhile, Princess Taiping continued to be highly extremely influential in governmental matters through Emperor Ruizong: she used his power without permission, and most chancellors, forbidden troops, officials and warlords were her associates.

Liu Youqiu and the general Zhang Wei (張暐), with Emperor Xuanzong's approval, planned to mobilize the imperial guards to kill several of those chancellors—Dou, Cui, and Cen.

On 29 July,[12] Emperor Xuanzong had Wang Maozhong take 300 soldiers to the imperial guard camp to behead Chang and Li Ci.

When Emperor Ruizong heard about this, he quickly ascended the tower at Chengtian Gate (承天門) to ascertain what was happening.

Emperor Xuanzong ordered her to commit suicide at home, and put to death her sons and associates, except for Xue Chongjian.

He was enshrined into the imperial temple, along with Emperor Xuanzong's mother Consort Dou, who was posthumously honored an empress.