Emperor Taizong is seriously ill by summer …
Years: 649 - 649
July
Emperor Taizong is seriously ill by summer of 649—with some believing that his illness is caused by his taking pills given to him by alchemists.
Believing Li Shiji to be capable but fearing that he would not be submissive to Li Zhi, he demotes Li Shiji out of the capital to be the commandant at remote Die Prefecture (roughly modern Gannan Tibetan Autonomous Prefecture, Gansu), with instructions to Li Zhi that if Li Shiji hesitates, to execute him immediately, and if he does not, to recall him after Emperor Taizong's death and make him chancellor.
Li Shiji, when receiving the order and realizing that his life is at stake, immediately departs for Die Prefecture.
(After Emperor Taizong's death, Li Zhi will indeed recall Li Shiji and make him chancellor.)
Soon thereafter, Emperor Taizong, after entrusting Li Zhi to Zhangsun Wuji and Chu, dies at his summer palace Cuiwei Palace.
His death is initially kept a secret, and three days later, after his casket has been returned to Chang'an, his death is announced, and Li Zhi takes the throne as Emperor Gaozong.
