The Road to Power from Concubine to Female Emperor
In her early years Wu Zetian entered the palace as a concubine of Emperor Taizong, and after his death should by custom have become a nun, but through her special relationship with the crown prince Li Zhi (who then succeeded as Emperor Gaozong) was able to return to the palace, thereafter toppling rivals such as Empress Wang and Consort Xiao and being made empress; as Gaozong grew weak and ill in his later years, Wu Zetian seized the chance to gradually take real power over the court, and after his death deposed and confined her own two sons in turn, at last formally taking the imperial title in 690.